here is the ideea :
On my h22 i want to do a 2.5 straight pipe ... From the headers pipe all the way to the back , small bend , into a dual tip magnaflow muffler .
Question is ... will not having a cat and almost no bends create a big problem for me because of lack of back pressure ?

 

I just did this to my h22/ek swap.. and it flies
in addition to what your suggesting, I also installed a 2.5" 'cherry bomb' glass pack that was 27" long.. the sound coming from the exhaust is a really deep, low rumbling, and not at all high pitched rice boy sounding at high rpm

 

Backpressure has been proven to be a myth for quite some time. I don't know why people continue to believe in it. Less backpressure is better. But you don't want to go too large on the tubing since this decreases velocity (which helps with cylinder scavenging). But you will not have a problem with 2.5 inch tubing.

 

heh gets my hopes up as right now i'm running dissapointing times on the stock exhaust ... i hope this will fix me up ... i'm concerned about my weight since i'm stuborn to run full interior on a 4 door and i want all motor 13's for it :D

 

what's a cherry bomb ?

oh yeah true that high pitched rev sounds ugly , is there any way i could keep this setup silent ?