97 240 headers and catback system

[2pleez]

Sorry to bother anyone but "yes" I am new here and have a question. I've been through the threads and can't find this specifically.

I'm trying to install a Greddy RS catback system and a DC 4 to 1 header. Problem is the catback is 80mm and doesn't match up to the header. I'm seeing all these videos on you tube with all the guys installing 80mm catbacks on their 240's. how do you accomplish this? Do I need to go to a machine shop and hack up my catback and weld on a reducer or what?

Thank you for all your time and patients

[Chaluska]

Originally Posted by 2pleez

Sorry to bother anyone but "yes" I am new here and have a question. I've been through the threads and can't find this specifically.

I'm trying to install a Greddy RS catback system and a DC 4 to 1 header. Problem is the catback is 80mm and doesn't match up to the header. I'm seeing all these videos on you tube with all the guys installing 80mm catbacks on their 240's. how do you accomplish this? Do I need to go to a machine shop and hack up my catback and weld on a reducer or what?

Thank you for all your time and patients

No...

even though the catback is "80mm" aka 3 inches, the header is typically a 2.5" outlet, which usually will go to a 3" in and 3" out cat (even the oem is like 2.85" diameter), then that goes into the 3" greddy exhaust.

just bolt it all together, it will work, and will be loud. make sure you use the gaskets, otherwise you may have leaks, depending on how warped the flanges are.


edit : also... the flanges are all the same size between 3" / 2.5" and 2". so if your worried about fitment strictly from flanges, it was all made to bolt together.

[2pleez]

Problem is when I put the header to the catback even with the gaskets there's still like a 2 8ths inch half moon gap on the top and bottom. That's serious blow by!!!

[fliprayzin240sx]

^^^Gap? So you're saying the flanges are 2 different sizes? Post up a picture so we can see what you're talking about. Usually, the flanges are all the same. The pipe/hole diameter is what changes so even if the pipe sizings the different, they would still bolt up to each other since the flanges match.