Hi all,
My exhaust has rusted out so I figure I may as well upgrade. I've read a lot of threads but being a novice, I would love some feedback on what I'm looking at. Car is a '98 Z24 convertible, all stock. I need to replace everything from the manifold back. I don't plan extensive mods, don't want it too much louder than stock, but would enjoy any efficiency gains (hp or mpg) though I know they won't be huge.
This is what I'm looking at, 2.5" pipes, hi flow cat, & 18" resonator from here: http://www.mandrelexhaustsystems.com/servlet/the-Car-Exhaust-cln-Chevrolet-cln-95-dsh-05-Chevy-Cavalier/Categories
paired with a Cobalt SS muffler. Does that look like it will suit my needs? Also, am I correct in thinking that it is worth springing for stainless since I live in WI, plan to keep the car indefinitely, and it only has like 140k on it? Would there be significant benefit to replacing the manifold as well, even though I don't have to?
Thanks!

Lightly modded you do not need more than a 2.25" exhaust. The longer the resonator the better, 26" neighborhood is a good place to be. That will help keep it from sound like a tin can dirt bike. If you're not planning on doing much mod wise, there really isn't much reason IMO to replace the stock exhaust manifold with a header. I don't know anyone personally with one, but I hear more people talking about aluminum exhausts which that site does offer too. I can't imagine it not holding up to a lightly modded motor and for less than a stainless it seems worth looking into.

I don't need more than 2.25", but is there any drawback to 2.5? This dyno test, http://www.iperformance.biz/dyno/exhaust01.html seems to indicate that the 2.5" performed a bit better on a stock Z24, and they are the same price, so that's why I was leaning that way. I'm not concerned about aluminized pipe not holding up to the motor; I am concerned about it holding up to the snow and salt on WI roads. I will have to look at longer resonators.

The only real difference you'll probably notice between a 2.25" pipe and a 2.5" pipe is sound. The bigger pipe will have a slightly deeper, mellower sound; and at least around here, it will be easier to find mufflers for as well.