Going onto a hatchback with b16a with JDM ITR 4-1 header with 2.5 inch collector.
Will this exhaust (TRUST) bottleneck my airflow????????

 

well if you search around, the typical catback sizes ppl are running are almost always 2.25 in or 2.5. i honestly think that you will not miss the .09 inches.

 

most likely thats fine. i run 2" straight back on a standard. runs better than w/ no B pipe at all

 

won't that defeat the purpose of the JDM ITR header?

 

think about it like this what motor was that exhaust made for

 

ah well if its a 2.5" collector you prolly want to leave it 2.5 all the way back. didnt read carefully

 

i have the jdm header and custom exhaust(very temporary) that exhuast is 2" the car is quiet and not very fun, however open it up after the cat and it's a different car....i'd def. go w/ a better flowing exhaust....especially if you upgrade your cams...