exhaust and intake questions
 

Ok well I finally picked up the z28 last week (pics this weekend, I promise). I pretty much knew most what there was to know about 3.8s and performance mods, but know I have to learn a whole new world.

So I thought I would just get some quick questions out of the way. The z28 drives like a cadillac compared to firebird, id like to keep it that way. As far as performance would just like to stay bolt on, car has 2.73s and nitto DRs so hopefully the 10bolt will last a while.

So I think first Id like to get some LTs. I was just curious, when people added LTs, did it effect drivability that much? Interior noisier? More rattles and vibrations? I was looking at some used QTPs with 3" y pipe. Hows the fitment and ground clearance?

LS6 intake and P/P tb. Seems like on tech they go for around 300 usually, but some come with fuel rails and injectors and i think egr provisions? or some type of emissions provisions? So what should I be looking for? I mean I can use my fuel injectors and other parts correct? I just need the intake? As far as P/P the TB, anyone local good? is it that hard to do myself?

Sorry for maybe some obvious dumb questions, the lsx series motors are just all knew to me and so much different then the 3.8 haha. Any tips or insight on what I should get, or what route I should go will be awesome! just let me know, im all ears. Thanks!

As for driveability with LTs there arent really any major issues it will be louder interior wise and u will get some vibrations and rattling...its only natural in these cars lol..As for QTPs not sure how easy they fit dont kno anyone thats used em personally..brand all depends on what ur willing to spend. U get what u pay for imo.

As for the LS6 intake u can get either with EGR or non EGR...id go for non EGR and get rid of all that crap, or u can get the EGR one which may be easier to find and just buy block off plates to delete it. U dont need to change ur fuel rails etc and most used intakes are around 300 so thats not a bad price. Also keep an eye on what ur buying when its used stuff most people dont kno the difference between an LS1 and LS6 intake they have different part numbers so make sure u look at pics before u buy anything. As for porting the TB Don does em for a decent price...U can do it urself tho but its kind of a pita.

Dont worry weve all been in ur shoes at one point..ull catch on they arent a hard motor to learn about or on

I wouldn't start with longtubes personally. If you don't change out the cat back first you aren't going to see any gain. If it were me I'd do a nice cat back (IMO Maganaflow) the LM1 is not a very good piece and makes more noise then power, a real LS6 intake (not the SLP EGR one) Delete the AIR and EGR systems and P/P the throttle body and see how you like it. The SLP lid is one of the best on the market so you should be good there. If you do decide to do headers keep in mind it gets exponentially louder when you delete the CATS, especially if you keep the LM1. The QTP headers are very nice and fit well but their Y-pipe is absolute crap and leaves around 2 inches of ground clearance and bangs all over the floor so I'd stay away from theme. Best headers I had were Kooks, big power gains and professional fitment.

definitely a cat back first and then go from there.

my brother is on the same ride and we'll be putting on his catback tonight. he's on a budget so we ordered up a Hooker c/b. (I have one and love it)
definitely get the simple stuff out of the way 1st. If it doesn't have a lid, get one. any vendor sells the SLP one for $100.

headers best bang for $ ARH/QTP//Kooks. all stainless. again based on budget your thoughts and options change. most of us that run the coated Pace setters love them, but know the risks of rust in our part of the world is high and you'll prob. replace them in 6yrs or so. (personally will likely splurge on stainless when the time comes)

and I'd look into new rear end gears

I really like the LM 1, I love the sounds,and its not as obnoxious as I thought it was going to be, only up top it is.

Ok so should I keep an eye for ls6 intake without EGR and just go ahead and delete that stuff.

Do those kooks headers provide good ground clearance? I wanted to keep cats, but from what Ive read its really not worth it. It costs more, more things to replace, and technically LTs are illegal anyway so even with cats im technically still illegal. So with a catless y pipe and LTs what would be a good catback that isnt really loud? I wanna still be able to pass inspection, but if I have a catback thats stupid loud I dont think my guy is gonna let me slide.

Im sure once I get the LTs and ls6 intake Im gonna need a tune right away? Not only for SES lights because of the EGR and cats, but will also run to rich?

thanks for the good info!! whats the part number for ls6 intakes? so I dont get screwed over.

I would love some 3.73s or maybe 3.42s, but that just seems like thats asking for trouble with the 10 bolt. Im actually nervous about throwing on my nitto DRs. But the BFG g forces dont hook up for crap, even with the 2.73s.

If youre gonna do full exhaust go for Magnaflow or Hooker, the LM1 will be way too loud after that. And gears really would make a world of difference, and by themselves dont make the 10 bolt any weaker, unless you get 4.11s. Its often easier and cheaper to get a used 10 bolt, just make sure you get the right one - 3 channel if no TCS, 4 channel for TCS.

Yeah LM1 gets very loud with longtubes and pretty much unbearable if you delete the CATS. all the GM LS6 intakes will be without EGR be aware that Corvette LS1 intakes had no EGR so make sure it is an LS6 (anything 01 and newer will be). And really for the mods you have now you should have a tune done. But def if you delete AIR or EGR you will need a tune and also if you do headers you also absolutely need to, so plan accordingly so you only have to do 1 tune

Ok, thanks for the info. So is slohawk still doing if you buy some kooks headers off him he'll install them? If I could just do my exhaust, ls6 intake and p/p TB all at once and get it tuned at his shop that would be awesome, and save me some coin on gas money driving up there.

hows the ground clearance with kooks? I heard that I think it was LPP the clearance wasnt great and they also would hit against the firewall or something, so youd get a bang every now and then, anything like that with kooks?

With magnaflow, will I be able to pass inspection? I know magnaflow is one of the more tamed exhaust down low, so you think itll be quiet enough to pass? Or will it louder then my current LM1 set up once I get the LTs?

is the new car a a4 or m6 that will make a big dif on what gears you get, i got 342s with a a4 car rips with those gears. i also got the LTS and a off road y pipe with dummy cats, the rest of the of my exhaust is the slp exhaust with duel out one side that came with the car and sounds pretty loud enough for me.you definitely want to make sure you get a tune set up after you get a lot of your changes. one other change you can do is change the tstat to a 160.

Yea its an a4. Since i Have 2.73s now would I have to use a different a posi or can I use stocker? Id love some 3.42s. Dummy cats? What are they just gutted? or hi flows? Id like to get hi flow cats just to help with sound and i think exhaust stinks without them, but I heard its really not worth it.

All this ls1 aftermarket is ridiculous, im now looking at 12 bolts and fast intakes.... haha. Cant wait for next summer!!!!

Kooks has about the most clearance you can get and have longtubes. No matter what you get they are gonna hang down some, nature of the beast. I am 100% sure Don will do an install for you and a tune if you call him up and make an appointment. DOn't waste your time on gutted Cats, either keep em or get an off road Y-pipe.

Pretty sure full exhaust with a Magnaflow will still be quieter than the LM1 with stock exhaust.

X2, and no drone

get rid of the junk 273s lol ull love the difference after they are gone..no worries with a 10 bolt when it comes to gears i just got rid of my 273s for 373s, A4s arent hard on rears unless u beat the piss out of em all the time. I have kooks and no clearance issues as well..my hookers were the same way. I def wouldnt do the LM with full exhaust like everyone says it sounds bad..id go with a magnaflow. Give Don a call and talk to him he should be able do all that stuff for ya in a one shot deal.

alright thanks for all the help. Im gonna save up this winter, then come next spring ill give don a call, with a nice list of goodies i want and need installed.

-kooks LT and ORY
-ls6 intake
-p/p stock TB
-magnaflow cat back
-3.42 or 3.73s (still on the fence? hows the a4 DDing with 3.73s? which brand? motive, richmond?)
-tranny cooler good precaution? or not really needed unless i went with a stall?

hows that list look? any input welcome. Stock plugs are still good for full bolts on right? no need to go to a tr6 or anything?

coolers are great idea, if you had a stall.


(personally enjoy installing things myself, call it bonding with the car, get to know her before you change her oil...) lol

A cooler isnt mandatory without a stall but its not a bad idea at all. As for gears, how much highway driving do you plan on doing?

cooler isnt necessary unless u plan on stalling it...as for the 373s i have no issues driving around town or on the highway...i used to cruise in 3rd all the time before so its no different in 4th with the 373s in now except performance wise lol. Its loud on the highway but its expected(gas mileage stayed the same as well)...342s would be just fine for ur car i went with 373s cause i wanted more and also havin to do with what i wanted to do with the car down the road...o and i went with motives.

If I could successfully install headers myself with a buddy in my garage, id probably be the happiest man alive haha. I have really limited time, space, and tools. It always feels nice knowing you did something like that yourself though.

I dont do much highway driving, but occasionally for a trip, car meets, or a trip to the track. Also with the 3.73s are you still in 3rd gear at the 1/4mi?

You should be, yes. Here's a useful gear calculator:

http://www.f-body.org/gears/

Keep in mind that doesn't account for converter slip, but will give you an idea of how those gears will perform.

for you to out run 3.73s you would have to be running low 11's

put 4.11's in.

Lol, 1 track mind!

but of course his is... it's the fast track. nothing else will do.

i want to see pics of the car

Makes it simple for people.....LOL

I like them for a street car.Makes 6th gear usefull on the highway and cruises at a sane RPM.

It's an auto Don :p

Still applies lol. Ran a 200 4r and 4.10's in my 68 for years. Ran it to Florida, Detroit, and all sorts of places in between :)

Yeah but you are talking alot of RPM on the highway, I believe it would be around 3200ish at 75

i agree on the rpms, i got 342s at 65 im running 2200.

Yeah depending on tire size. I was around 27-2800 with a 28" tall tire and the converter locked up.
So much fun all around though ;)

Oop's, should of read the whole thing...LOL

3.42's then. 3.73 is too deep for a stock motor.

Then of course a good converter will do wonders.

Even with bolt ons(like ones I listed) 3.73s would be no good? I was kinda beating around the bush now and was leaning towards 3.73s, but you know way more then I do, so just let me know what you think. These 2.73s kinda stink, I feel like my bird launched harder, a4 w/ 3.42s that came stock, why isnt that an option the a4 v8s?

Also, Don, do you do gear installs? What would I be looking at for just gear install, and just tuning the pcm for new gears?

Would be around $600 for gears,install,gear tune.

For launching and just WOT runs the converter would gain alot more.That is $1350 for yank converter,cooler,tune.

Of course converter and 3.42's is the best.

so i would be looking at pretty much 2k for those two items. I saw a guy with stock z28 pretty much, with 3.73s and 3400 stall run 12.4 or something stuipid like that. Very surprised.

What size yank stall with the 3.42s, it will still be getting daily driven, ive heard all mixed opinions on how DDing with stalls are, guess it depends on the application too.

12.4 isn't that impressive for a stalled LS1. And IMO before you do a stall decide if you want to change the cam or not because there is no sense in doing it twice.

We have a pretty good handle on stall selection. I like daily driven cars with a tight stalls. Had a customer run 11.9 with stock manifolds,no cats, 3.42's,lid and stall.(tight street)

Thanks for the info, As for cam, I wont be changing cams. Thats the reason I want to just go gears/stall. Right now I love the ride quality, the exhaust isnt loud and Im not struggling with exhaust parts coming loose or giving me ground clearance problems.

By tight stall you mean, it wont feel like its slipping much, correct? 11.9?! Thats unreal and really makes me want to go this route. Don, I will be in touch for sure this spring!!! Im gonna get some track numbers the way I am now, and Id like to still get a little more seat time with the ls1 before I step up and make it even quicker.

What kind of stress will a stall be putting on my transmission though? Would I need to be constantly worried about it? Or have guys run stall on stock 4l60e's no problem? Car would only see the track maybe one or twice a month once its nice out. Only 54k on the car.