N1 exhaust

[Jass]

Ive got a 2.5 inch tip too, with a baffled muffler, and ive got the same performance as the canon that i had before. Costa is right, stick with a quiet system, last thing thing you want is a yellow canary hanging from you car.
2.5 inch is probobly the ideal size for a cat back exhaust on the astra, as for the size of the dump pipe (i think that the size of the original pipe from the turbo is 2.5??) 3 inch should not cause a problem.
Anyways the bottom line is you choose what you want for your car, trial and error seems to be the way to know what works for you

[Anonymous]

if you want to be faster than the other guy you will need to spend the bucks on your exhaust ,other wise leave it stock

[Anonymous]

well the saying goes "you get what you pay for..." find a cheaper place, sure both places may give you a 2.5" exhaust bla bla bla, but i'm positive you'll be happier with the one doing it for more $$$. Workmanship is better, performance will be better and most likely you wont be going back for changes.
If your gonna do something, just spend that little bit more and get it done properly.