hey guys im new here...i drive a 98 civic SI but its canadian so its basically an EX...which starting to transform into a sleeper basically...no loud tin can exhaust or eurolights that kinda thing

anyway...i put in my AEM CAI yesterday, its pretty sweet, nice low sound, noticable power increase but nothing serious
i ordered my DC 4-2-1 header today should be here in about a week...and then depending on the amount of money i have left i will order an apexi world sport 2 exhaust either on friday or 2 weeks after

now my question is...since the header and exahust will be aftermarket, will the stock cat between them just ruin it?
how much benifit will i get from a high flow cat?

 

since your changing it all, you mide as well stick a hi flow cat in there..it will only increase HP like by 1 or somthing stupid like that, but it will make the air from the intake to out the exhust REALLY nice which will increase your HP but a nice bit, so..DO IT!

im from canada too BTW