Never ending quest for the best C4 ZR-1 exhaust system- Stainless Works

[mike100]

Been back and forth with a few different pipe combos- but the long story made short is that the 3" all the way back with the SW 3" X-Pipe makes great top end with plenty mid range torque using LS7 cats from a C6 Z06. It is faster than the stock mufflers on 2.7" pipe without cats. It's Freaking Loud, but then running stock muffs catless on longtube headers was a bit obnoxious too. There is drone, I will probably go to turbo mufflers again when I get some more money to spend. Additionally, I really like running catalysts again. Birds don't fall out of trees when you drive by, you don't get dirty looks from the beach hippy in a Prius, and it quiets things down and quells those decel backfires quite a bit. Lastly, I priced various aftermarket bullet cats with a 3" slip connect, but how can you beat factory Cats from a 505 hp car? You can tell it is running clean, the pipes aren't even blacked up yet and there is no odor at all. OEM parts FTW.











I had recently installed some LT5 headers and I found these 2" longtubes that were already setup for air injection. These aren't SW headers, but a mystery brand- maybe made by Morrison Motorsports in GA is the best guess I have so far. Anyhow, they fit perfectly and really woke up the car.


I was running cat-less for a couple of months after the header install (using stock mufflers), but I got tired of my eyes watering every time I pulled up to a stop light with my windows down. Since I had some oem LS7 exhaust that was a stillborn modification on my C6 that I decided to not go through with, I put those nice 3" piped cats to use. They are pretty compact and just fit under the heat shields in the tunnel.

[mike100]

Notice that we were able to retain the use of the clamping system so the pipes can be separated for service.






..
Factory air injection still in place. Does this car even have headers?? Stealth- Because California.

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Also I got a good lesson in installation technique at my local muffler place. Check out the diff clearance. Perfect 1/4" spacing at rest. My old B&B sure wasn't able to achieve this, but it does have a lot to do with jacking up the center piping in place with a jack of some kind, then tightening the clamps before letting it hang.



more pics:

[mike100]

and the pics from the group buy thread:

[FU]

Real nice job Mike !

[-=Jeff=-]

Those might be Watson headers

[GOLDCYLON]

Originally Posted by -=Jeff=-

Those might be Watson headers

Concur. I would have had em coated as well but that might have not have been stealth enough for CA

Interesting rear tips really fill out that cutout

[Dynomite]

Originally Posted by GOLDCYLON

Concur. I would have had em coated as well but that might have been stealth enough for CA
Interesting rear tips really fill out that cutout

SW started shipping the Exhaust with the SW rectangular single Outlet as I installed recently on my 90' vice SW twin round pipes as I have on my 91'.
I like the looks as the New Style Outlets match the cutout perfectly

Nice Photos Mike and not too many notice the gap between Exhaust and Differential but here is another idea

SW Headers ZR1CORVOR and SW Exhaust ZR1CHAMSW were installed on both the 90' and 91'.

For both the 90' and 91' a Copper spacer was added (1 x 6 inch copper pipe with pipe end caps and pipe coupler) to keep SW exhaust 1/4 inch away from Differential Housing.

Copper spacer added (two each 1 x 6 inch copper pipe
with coupler and end caps) to keep SW exhaust 1/4 inch
away from riding against Differential Housing. The end caps
and coupler actually keep the spacer in place without any ties.



I set the two rear hangers so they pull the exaust up tight against
the copper spacer. Also set the rear "L" hanger so there is freedom
of the exhaust system to move to the rear at least 1/2 inch when hot.

[mike100]

Originally Posted by GOLDCYLON

Concur. I would have had em coated as well but that might have been stealth enough for CA

Bingo

I'm also considering dually out with a pair of conventional tips because the best way to make these c4's stop resonation from the back hatch area seems to be stopping up dual outlets to a single one...like Corsa's do and GM as well with the factory fake 2nd outlet. I think it's about time to figure out how to get the NPP valve hooked up on my car. Also very likely will go to some quieter muffler type as mentioned in my first post.

The main question I have on GM's NPP system is what controls the valves to open up at roughly 3500 rpm besides low manifold vacuum? If there is electronic control, how do you adapt it to older cars?

[vilant]

Wow, sweet job. Have any video of how the new exhaust sounds?

[mike100]

Originally Posted by vilant

Wow, sweet job. Have any video of how the new exhaust sounds?

I'll try to make something on Saturday when I return home. It does sound great when you are going for a 10 mile drive to open it up and play, but difficult to travel a highway in for any length of time in 6th gear.