Some exahaust questions, could someone give me the run down? Options

[tonytutino]

Ok so here's the plan: i would like to get rid of my stock exhaust piping, get a new muffler ( i got some nasty 3A racing one right now), and get a high-flow cat.

1) i want 2.25 piping so should i buy the 2.25 high flow cat? it may seem obvious but i really don't know.
2) we don't have emission laws here, should i get a test pipe instead? (whats the difference)
3) does the inlet of the new muffler need to be 2.25? alot of the ones i'm looking at are 2.5 and i didn't know if they welded some kind of adapter or something on there.

i guess thats it, i'm a newb when it comes to exhaust...

thanks in advance!

[tonytutino]

oh well indeed

i think i read somewhere though that you only get 2-3 more horses on a dyno if you get rid of the cat. and i'd rather be a little more eco-friendly if it just means 2-3 horses. i wouldn't really feel that.