does removing the cat and going to 3in pipe from the turbo back improve hp that much or does open down pipe work just as well
will running open down pipe hurt my car

right now i have:
Apexi intake
Apexi safc
hks down pipe 3in
hooker exhaust 2.5 or 2.25 not sure (stock cat)
mild street port
mazda trix 2pc 2mm apex seals
mazda trix silicone hoses

my friend who knows alot about rotarys said i was choking it out but i dont know how
what mods should i do next i dont want to blow it up but im still learning about rotarys and im not sure on what i can and cant do and the order in which they need to be done

 

i think what you are asking is about a midpipe(goes between the DP and Catback; eliminates cat)

The problem with the midpipe is boost spikes/creep. Do a search under midpipe and you should find more info than you will want to read. I would recomend a high flow cat, but that is just my 2 cents.

 

A high flow cat wouldent be as loud as a midpipe, but with mid pipe you would need some kind of boost control.