I didn't want to hijack the guy below who is asking about header and Y-pipe combos, so here is my question/situation:

My '99 is my little "go to work" car. I am really fighting the urge to mod it, but there is so much untapped potential in a stock F-bod that it is proving impossible to resist. I do not want to spend much $$$ as I am trying to save up for a few projects on my '94 (hehehe...), and I vividly remember my hamburger hands after a couple F-bod header installs.

Anyway, with that explanation out of the way, here is the question: which y-pipe would be a nice direct bolt-in on a an otherwise stock '99 M6? I want to keep the cats as my county is looking to go to sniffer testing and don't want to fork over the bux for hi-flow cats, etc.
I want to gain a few HP, improve the exhaust note, but still look stock (that's why no cat-back) and not spend a lot of $$$.

So, which Y-pipe has been shown to be a nice direct bolt-in and proven to deliver a decent power gain?

 

I'm not really up-to-speed on the latest stock replacement Y-pipes on the market, but historically this has not been a very worthwhile mod by itself. Plus you open yourself up to banging issues as well since most all aftermarket pipes use round tubing. IMO you could probably spend the money better elsewhere... How about an SLP dual-dual? Looks and sounds pretty much stock

 

To answer this question directly, I don't think ANY will do. I used to have an SLP Y-pipe, but I also had a cat-back... I probably picked up a few horses, but don't know for sure, plus it costs $199.

Some argue the stock "flat" y-pipe "ain't that bad!", while other's swear it is restrictive. In any case, with the rest of the exhaust system being stock, I don't think it's worth it.

I'm not quite sure why you would not consider a less expensive catback system, that is not too noisy for you needs. A Hooker cat-back would be a nice improvement for around $300. Also, Magnaflow sounds great with cats for about $300. Neither are obnoxiously loud, and you will definitely gain more power with these as opposed to a Y-pipe.

Also, you can also get a highflow lid for about $100, and do some of the "free" mods. If you want more power for a cheap...

But if you are looking to get a better exhaust note, and a few ponies, I would recommend Magnaflow, it sounds great cruising around, and really comes to life when you get on it.

Good luck in your decision.

Tommy

 

You could do what I did to my ta do a catback but keep the stock tips non f-body gurus cant figure out why the car sounds different.

 

The SLP Y-pipe did change my exhaust note. So it
likely opened it up some. It also required 3 under-
car sessions and some serious beating on the cross
brace and a little dimpling of the pipe to get it
not to bang (convertible).

My SS came with a Y-pipe that was mostly stainless.
But the driver's side, "flat" part is mild steel and
looks like maybe SLP cobbled in some fatter, flattened
pipe? The stock Z/28s I crawled under before buying
didn't look quite the same. Maybe there's more to gain
on a true GM stocker. Or not.

The SLP piece is all stainless and it's of good quality
especially in the merge collector, where the one that
was on originally looked like a hack job (and I know
one when I see one, being a hack welder myself). You
can often see used ones for under $100, and this is
how I picked mine up.

I don't think the SLP dual/dual is anything other than
a decent cat-back with 2 pairs of chrome tips. It
had the same rating as the CME option, for the SS package.
You still need a Y-pipe, stock or otherwise. It's not a
true dual exhaust front-back, only after the muffler.
But the I-pipe may be slightly larger than stock, as my
CME is 3.25" OD.

 

Guys,

Thanks a lot for your input. Appreciate the candor and straight forward comments. Based on your answers, I will not be doing a Y-pipe swap. As far as a cat-back, I am holding off. I want the car to look stock and still be my "quiet car". Kinda sick when a stock Z28 seems like a Caddy to me.

I am saving up my pennies for a complete BMR front end with Hals on the '94, therefore I am being very frugal with the '99.

 

Dont worry about about the inspection Todd *cough*