back to the question at hand... I would think less then 12hp should be expected out of any aftermarket catback...remember its a cumulative effect...if you dont unrestrict the first part of the exhaust ie headers, ypipe high flow cat...the rest of the exhaust wont do much for you...im sure if you did some long tubes, no cats and a borla or loudmouth youd probably gain close to 30hp at the wheels but its all the mods for a specific part of the whole process that makes the most power....think of a funnel only backwards small end being the stock manifolds and cats and the large end being the borla at that small end it would only allow so much liquid/air to escape but then after that part ends you get to the larger side of the funnel and it lets all kind of fluid/air through. I hope that helped...also as far as mods go with seat of the pants feel...i think there are only a handfull of mods that you can actually feel...tq converter, gears, poweradder ie nitrous, blower, turbo, cam & heads thats about it....unless you do a full exhaust system its impossible to feel the difference...2 reasons i feel this way...on my truck when i did the blower i ran over a full second quicker and 10mph faster in the 1/4...that you can feel...i didnt feel the difference with my hypertech, i didnt feel a difference with my dynomax cat back...i didnt even feel a difference with my electric fan though it netted me .3 tenths in the 1/4 over my stock acces. driven model...it takes a lot to be able to feel a mod unless you have a super *** for this kinda stuff i obviously dont.

lata
Bill

 

Thanks for all of the great feedback guys. The Borla is my first step on the long list of my future mods. The non-flattened Y pipe and headers will hopefully follow in the next 12 months or so, as money and the wife allow.

I guess I was just fed up with the stock sound (or lack thereof) and I wanted to get something that flowed well.
For me it seems the Borla adjustable was my best choice, especially considering how sensitive the cops are in my area. In the local traffic court, I've seen plenty of guys fighting tickets for loud exhausts (while I was there fighting a ticket for no front license plate frame). I stayed away from the Loudmouth and the GMMG for just that purpose. Hopefully the Borla will give me the sound and performance I'm looking for without being a magnet for my local police.

Speaking of stock/factory sound, it's almost embarassing to have a Z28 as quiet as it is right off the showroom floor. I was next to an '03 SVT Cobra yesterday in traffic and the damned thing sounded awesome - still had temp dealer tags so I'm assuming it was the stock exhaust. Even a stock Dodge Ram contractor's pickup with the Hemi sounded good at idle in traffic.

 

There's nothing wrong with my car, thanks.

I'm sorry you feel that your *** is a great horsepower measuring tool.

Also, I did not say my exhaust outflowed yours. The last thing I want right now is another pissing match between exhaust brands, which is what you're looking to start. My original point was that I seriously doubt anyone can feel the difference in horsepower after installing something as simple as another catback. Will you feel a rumble? Sure. Will your car sound a hell of a lot meaner and make it seem like it's faster? Probably. Can you tell there's a horsepower difference by sitting in it? Doubt it.

But then again, I'm sure if someone sat you blindfolded in one LS1 car with a lid and another that was stock and floored both of them, you could tell which was which, right?

 

And I'm sorry your car's not powerful enough to provide the same feel. Stop getting your panties in a wad, we're just sharing information here.

 

I'm not getting pissed.

I just find it amusing at best how you can somehow claim my car is weak because I don't claim to feel a 10hp difference. An exhaust is not a supercharger. Like I said, I'm sure if someone threw you blindfolded in each of those aforementioned cars I mentioned in my last post, you'd really be able to tell the difference...or at least, you'd probably think you could.