I have a b16 swap with a thermal catback, which I believe is only 2 and 1/4 inch mandrel bent. I searched and didn't find the answer to my specific question. Is this exhaust size (2.25) rescritive for a B16. I was also considering getting a 4-1 header but would that help any when the smallest part of the exhaust is 2.25. The old "only as strong as your weakest link," saying. What size exhausts are you guys running with a 4-1 header and a b16. Any help is appreciated.

 

get a DC 4-1 type r knockoff with the 2.5 collector. 2 1/4 exhaust will be alright, if you do cams or any higher compression stuff, go with a 2.5

 

so should I expect some power gains with a 4-1 header? If I do get 2.5'' is that gonna have to be custom? don't think anyone makes one for the crx

 

I have seen a 3" so Im sure someone makes a 2.5

 

When I installed the Thermal cat back on my 88 crx si w/b16 and dc 4-1 header it felt a lot faster, but previous to that the way I bought the car it had shitty *** non-mandrel bent piping with a flowmaster muffler on it... I was pleased with the Thermal, nice sound too...

 

so would you guys think a 4-1 is worth it with the thermal?

Also thermal makes a 3 inch for turbo'd cars. I haven't seen a 2.5 inch