RedZMonte

thought i would share what i have done in the last week and give some feed back. I got a set of LS7 Exhaust manifolds, downpipes and H-Pipe from a buddy who went with a set of LT headers. The install was a pretty easy (except starter solenoid broke and had to order a new one). I installed a pair of 3" Magnaflow Spun cats in place of the OE LS7 ones that were gutted (car they came off was turboed at some point), the cats are pretty much exactly the same length as the OE just narrower which made the install easier. I followed "MadMatt's" install for any adjustments... I was able to fit with slight bending in the AC line rather then trimming the flange.. the manifold went down and i bolter the DP/Man together then bolted to motor (made it alot easier). I also added O2's to the LS7 H pipe for my secondary O2's. made a smooth taper to go from the 3" H pipe to the stock C5 H pipe rear tail pipes to muffler so it flows awesome with stock Ti's. (not pictured). During the install i did a EE Tunnel Plate, Special thanks to EE for getting me hooked up with one fast (it shipps in the same town as me so i had it the next day after ordering).

Along with the exhaust i added secondary Air injection ports to the manifolds to keep all the stock emmissions equip. on. I will have the info on that setup this weekend when its installed. And some GMPP 8mm plug wires busy weekend and still came in less the HALF of a set of Long tubes

The Drive is AWESOME, the car has a much smoother power band. It pulls harder and just even sounds smoother... got rid of the silly C5 exhaust gingle and made it slightly deeper and maybe a tiny bit louder.. (still sounds stock). This is a great mod for anyone considering doing a Upgrade and keeping in line with Emissions. I will in the near future get a Dyno tune and will update you with what i see. I will show you how i did the AIR injection and try to get a good pic of the reducers my guy made.

The welding and some of the custom parts were done at Collins Muffler in loveland, thanks to Scott and Ray (guys are studs, they have done work for years for me), so if any colorado guys need some work i would recommend them.

Modded Manifolds/Downpipes:


Drivers Side installed (secondary air capped):


Manifolds/Downpipes Installed:


H-pipes (3-2.5" reducer not installed or welded together)

RedZMonte

3"-to-2.5" Reducer on H-Pipe:

skyavonee

Cool project.

vinceg

Also my next mod. Not a big HP diff. from LT's

MY03C5Z

Nice work! What are the hp differences over stock with this swap?

RedZMonte

HP gains are simmilar to LT headers. the LT headers will gain more TQ then the LS7/LS9 Manifolds. These are Stock OEM parts so it is a great upgrade for 1/2 of what a LT header will cost and will be easier to sneek past any emissions inspections like in CA. IF i could have got the exhaust shop to cut out the cats from the DP and install them in the H-Pipe where the stock C5 cats were i would be even happier but they wouldnt touch it unless the car was there and it would have cost alot more labor for the things i did myself. but hey what can you do... The O2 harnesses are about the only thing i had to tuck up out of the way from heat, everything else fits perfect.

As for the AIR, the driver side will be easy, making a new pipe to connect to the stock check valve. the passanger is a Pain and i dont want to take off the UIM if i dont have to.. i will cut the stock tube and add a high temp 5/8 hose and attach another check valve (so it will have 2 on the passanger side) and a custom pipe connecting it to the manifold. I found "BWD CV8" check valve for 12.99 and is exactly like the OEM one except the inlet is slightly smaller then our stock valve, so a 5/8" hose will fit over it unlike the stock one.

RedZMonte

A.I.R. hooked up now with custom tubes connecting to the manifolds:
Drivers Side:


Pass side:

spiral04

Nice

zeevette

So, with the fab work, and labor, was it actually half the price of a self-installed LT system? Personally, I'm glad it sounds like it's not stock.

RedZMonte

I'm about $650 all in total, but that also includes the new cats, install of the cats and all fab work. If the stock cats were not empty I would be in them total ~$200-300 (got the exhaust parts free from a friend). It sounds really good, deeper and a little louder I'm very happy with the setup and now that the air is hooked up, I'm not getting AIR codes

zeevette

Pretty good for the money. You should dyno it, to see what difference it made.

RedZMonte

Next investment is dyno tune... Going to be a little bit before I get it done tho... Will be sure I post the results.. Even if I don't get a lot of power gains, the drivability is much smoother and the sound is great.. I expect ~20whp after tune, if its higher it will be great but i don't expect it to be much more if it is. LS2's pickup 30whp from the swap and ~20wtq.

RedZMonte

Going in Tuesday for Dyno tune then E-test. Etest just barely failed with the smaller cats.. High HC's.. Stock C6 cats i think would be fine.. these magnaflows are small and its loading up fuel on decel. Hope tune will clean it up, everything else passed with flying colors. Clint at AiR in Denver will be doing the tune and i will have Dyno sheet to go along with it. Will post.

S

zeevette

We're lucky here; no sniffer test.

RedZMonte

Dyno results are in.. Big thanks to Clint at AIR and Bear at Dyno Pro! anyone in the denver Area should definalty consider going to them for the tune/dyno. This is a SMOG tested street legal setup Oficially (Have the passing E-Test to Prove it)
Sorry i dont have a TRUE bone Stock dyno to compair. But others 02-04 i see dynoing 350-365HP Stock, so looks to be a 20+hp gain on a street legal alternative to cattless headers at 1/2 the price.

Mods:
* Breathless performance CAI
* Aftermarket Airbridge w/ Coupler and Halltech MAF screen
* LS7 exhaust manifolds & H-pipe to stock Ti mufflers
* AIR tune http://AI-Racing.com/


383.41 HP 358.83 TQ

PeteZ06

wow... awesome gains!!

2003corvettez06

video? would like to hear the car with some revs plz

RedZMonte

I will see what i can do.

S

mchicia1

Good work, it's a great budget setup for sure. I am running my setup with a 3" XSpower midpipe, which you can get for $100. I connected that to the XSpower 3" catback. I just cut the c6z hpipe, and slip fit them together and added a clamp so I can keep them adjustable. This setup sounds wicked, I love it. I had a corsa pacecar prior, but I like this much better. I used the factory cats. All I had to do with shave a little off the manifold on the pass side to clear the A/C line with a grinder, took 2 mins. And I had to use a button head bolt on the driver's side inspection cover because the stock bolt was hitting the cat.

scottieg74

Di you think this set is will yield a higher horsepower gain than shorty headers and high flow cats?

Im curious. I want to mod my exhaust i just dont want the headaches of trying to pass emission checks in Vegas with long tubes . Right now my exhaust is stock with Flowmaster force II axelbacks