so i got a parts car that had a jdm 4-1 header on it. i decided to take off my dc headers which where pancaked on the bottom. as i expected, nothing fits. but its cool because ia m throwing on a full magnaflow 2.5" exhaust setup. my main wuestion is what size is the collector on the jdm 4-1 header. a stock 2.5" flange i had did not fit even close. not sure if i should get a 3" collector. the parts car did have a ball type collector flange on it but it dident fit very good so i dident want to reuse it.

 

i may of found my own answer

http://japaneseengines.wordpress.com...llation-guide/

so will i have to use a ball joint collector. i have about 6"of space from the header flange to my 2.5" high flow cat. so i want to add in a flex section

 

ok i am going to order a flex section like this



http://cgi.ebay.com/ebaymotors/2-5-S...Q5fAccessories

but i may still need a larger ball collector. i just need to know what size ball collector works best with the jdm 4-1 header.

 

a flex pipe will work, so will solid tubing. if you keep the ball joint you might as well save the money on a flex pipe and just weld in a straight piece. if you do away with the ball joint then yes the flex pipe is needed.

 

so what your sayling is the ball joint acts as a flex pipe. hhhmmm. but what size ball joint fits best. i know ill need a larger one then a 2.5"

 

???

 

you must be measuring something wrong. the jdm itr header is a 2.5" collector. that means 2.5" pipe. how big the mushroom is doesn't count. you could run a jdm itr header and jdm cat and have the whole thing bolt right up you know.