Working on a new 3" stainless X-pipe setup for the Camaro, it's about 80% tacked together now, and I'll hopefully have the electric cutouts coped into the system in the next day or two. A similar setup will likely work for torque arm cars (mine doesn't have one), as long as you have that Hooker Transmission Crossmember (Mine is a custom one I built to get the clearance). The muffling will be via consecutive Vibrant 12" bottle resonators, and Vibrant Ultra-Quiets.

Edit: Holy S*%&, I apparently just crossed TWENTY years on TGO ... My god, where have the years gone. I've had this car for 26yrs now.

 

looks great.
i did a full stainless exhaust once.
never again.
after the cost and all that, i change my mind on sound too much and cut things apart and rebuild them.

 

I'm not saying I won't do it again, but it is shockingly expensive, and that's even if you already have all the tools and equipment!

 

I'll be watching this with interest. Especially the cutouts and where you determine the best placement is for maximum pressure wave tuning. I've this idea kicking around in my head for a decade or more!
As for stainless, I've never really understood why.
I have a 2 into 1 y-pipe that's 2-1/2" stainless and it connects to the 3" mild steel cat back and then over the axle.
Twenty years on and both parts are none the worse for wear. So the mild steel has held up perfectly well.
Next time the exhaust gets reworked (it's a major league power sucker as it is with a single Chokemaster muffler) I'll ease the cost burden and use conventional tubing.
Looking forward to your efforts.
Yes sir, where does the time go...!!!?

 

Right? I mean, the stainless is mostly because it's pretty and it stays pretty. Value there is subjective, of course. The previous exhaust is about 25 yrs old, and it looks it. Not rusty, but pretty grimy and beat up.

I'm not overly concerned about pressure wave tuning and such, as there are other concerns that make a WAY bigger difference, and then are further constrained by packaging in these cars. Like, having an X pipe, vs no crossover. Having a cutout that's as close to straight through as possible vs not.
I know opening the old mufflers (on the pinch bent, although fairly straight exhaust) as opposed to through the S-chambered mufflers, was worth 4-5mph at the track.

There were some great engine masters videos where they showed with A/B tests how little of an impact most seemingly major changes to exhaust made on measurable power, up to and including bashing in the header primaries with a hammer ... and it shockingly made almost no difference, even on the dyno. So I'm trying to get the big stuff right, and make it look a way I'm proud to have made it, while also quieting it down a little through the mufflers (I'm getting old lol), and make the car more enjoyable to drive.

Thanks for following along! I'll have more updates shortly. I'm working on building the Y-merges with straight and mandrel bent halves to accommodate the cut-outs now.

 

I take that engine masters stuff with a pinch of salt really.
I've seen too much where exhaust is vital to engine performance if the rest of the package has been optimised. I'm at that point with the only thing holding me back engine-wise is just that.
There are plenty of real world tutorials on how effective pressure wave tuning is. This is why the truly fast NA cars have open headers and tuned length collectors. Drag racing, Circle track (as in modifieds ) all use collectors of a scienced out length. Even those restricted to having to use mufflers use one of such a design and placed appropriately that it duplicates open atmosphere.
Check out the Pipe-Max engine software if you haven't already. Very insightful.

Now that said and racing aside, I agree that there is plenty to be addressed on the exhaust side as you mentioned.
I'm living proof.
~450 HP as realized on a dyno will not produce even close to 450 HP if it's forced through a single 3" pipe and muffler that flows barely 300 CFM. It just can't!
I placed a single 3" cutout right the 90° bend before the traverse muffler at the back and picked up a couple of tenths and a similar gain in MPH trap speed in 1/8 mile. Those were back to back tests. Same day. Same track. So I running with that idea as I know it works.
I'd even go so far as to keep my single system in place and modify the y-pipe to incorporate cutouts strictly for track days. Uncap them and race.

At the very least, as you also suggest, is a well designed system. X-pipe. Reasonable pipe sizing. A couple of mufflers that should pass at least 2 CFM per HP produced. (450 HP needs 900 CFM of exhaust flow capacity to not limit output. That too has been proven.)

You're most certainly on the right track with what you're doing. I wish I was in the process of doing it too.
Keep posting your progress!

 

I'm not disagreeing, I think I've just reached the other side of the bell curve for optimization haha ... the differences exist, but at 1,000hp+, you can't feel even a 100hp difference, plus or minus on the street at all, so I'm not too worried about it for this application. When I spent 2 days every week at the track, I for sure would have. Also, if I get around to building new headers, I'll be a little more precise about that, too. I also did a back-to-back on the old setup at Sonoma raceway a few years back, because I ran it open, and they told me I was over the 118db limit (like,wut? haha). So, I put the caps back on the mufflers, and ran another pass, and it went from 143mph to 138mph. Pretty significant.

 

Yes. That's the significance I'm looking for too. Although more like 110-115 MPH. Little NA 357 here @ 3500 lbs.
One thing I'll say is that you forced induction guys do tend to skew the curve. Bringing your own atmosphere is pretty handy. I'm not into turbos but the idea of a supercharger, centrifugal or otherwise, does have its appeal!

 

Fitting up the reverse Y-merge for the cutouts (there will be 2 of these). Man, this was not simple to do. Huge respect to pipeline welders that do this flawlessly with 4' diameter pipes lol.
These will go right at the rear axle, and the straight section will have the cut-out attached on the end. The curved section will actually get cut back to where the line is visible at about 55 degrees, have a straight stub added, and head towards the mufflers

 

What do you got goin on with the rear suspension. Are those inboard boxed lca?

 

Yeah, i saw those too, are they old southside machine lift bars? There were a few companies who made them back in the day. I haven't seen them in years!


this exhaust looks great!

 

Wow, great eye ... yeah they're the SSM lift bars! They're incredible ... or at least, they were when I drag raced twice a week all summer haha. The car always launched straight and dead even, and only ever got out of the groove once or twice in thousands of passes.
On the street, they're ... fine haha. I have toyed with the idea of doing an IRS though, since I basically drive this thing around L.A. to go to cars and coffees now But, it is a bummer that no one makes them anymore, although they're simple enough to measure and fabricate a new set if you were so inclined.
Thanks! I'm excited to get this thing welded up and see (hear?) how it sounds!

 

Dude, I wanted them so bad back in the day. I used to have all sorts of wheel hop issues and thought what better for strip use. Then they disappeared! The truth is, back in the day i had no business w them!

 

The photo in my signature shows you how well they work! The car has never wheel hopped once, and it does sick burnouts lol.