Magnaflow is also the only out-of-the-box cat-back system for the Vibe (that I know of). The only other options are to either go full custom with your choice of cats, reso, piping and muffler, or go with an axel-back (borla, thermal R&D, TRD or now Vibrant) + a JP midpipe. I am not sure, but I seem to remember seeing a post that reflected slightly better gains from TRD axelback+JP midpipe vs. Magnaflow cat-back, but I'm not sure. I KNOW the cost would be double. Really, the JP midpipe would be a viable option for anyone that already has a cat-back and doesn't want to spend more for Magnaflow or ~$200 more for full custom. The JP midpipe is not cheap, as this group-buy thread shows that it ran MORE than the Magnaflow itself:
http://matrixowners.com/forums/-t40999.htmlYes I know that's for the 1zz, but I think they have one for the 2zz too.If you can get away with it (i.e. emission controls in your state), a custom exhaust with high-flow muffler, resonator, and 2.5" diameter piping would be optimal. Anything over 2.5" might lower your backpressure too much.