Quote Originally Posted by yellow-dc2 View Post
cat back will not change anything but the sound of the car.
If the correct pipe diameter and muffler/s is selected there could be very good gains with just a catback..

A intake, header and catback setup could get u a nice hp gain on a N/A motor..

I took my civic for a 1/4m run straight after my B18c convertion and only managed 14.7 with stock exhaust, SRI (k&N) and powerFC(untuned)
then came back with a 2.5 pressbent catback( same header, cat)
same SRI pFC still untuned, and did a 14.2 pass.
picked up 3mph aswell.