I currently have a Thermal Catback exhaust w/ stock cat and headers. I’ve read on some threads here that going from small header size to largers to the catback is beneficial. I’ve searched and have not found a definate answer really. My main question is WHAT SIZE SHOULD I GET MY HEADERS AND CAT for my catback if im not mistaken Thermal has a 2.25 catback exhaust. Any info would be appreciated thanx.
theres only 2 real sizes
2.0 collector to fit the stock cat(most 92-93) headers
or 2.5 JDM collector .you will need a new cat flange(itr headers)more performance
so then most performance headesr like dc , kamikaze etc. have a 2.5 collector i assume.
You also need to pay attention to the design of the header. Tight turns are bad, and you should compare the primary tube diameters. You want fairly large diameter piping for free flow, but at the same time you dont want it to be too large, because you will lose exhaust stream velocity. Basically, each pulse of exhuast could slow down and really screw up your performance. When you have too large piping, you lose a lot of low end torque (but you gain hp in the top end, to within reason).
My 5.0L engine has a 2.5" system on it, and that’s plenty good for the street. Maybe I’ll upgrade to 3" if I get a 5.7L engine.
But, of course, my engine only revs to 5000 RPM. :squint:
What does someone suggest for headers size and cat size for my Thermal Catback which has a 2.25 piping.
You’re not going to see any gains with bigger piping if the catback is still 2.25. If you go 2.5" headers and cat, into a 2.25 system, it will only flow as well as the 2.25 part will let it flow, because that is the bottleneck. I would suggest you go 2.25, or 2.5 if you ever want to upgrade the catback later on.
My setup is a DC Sports Ceramic Header (2" Collector), 2" Carsound hi-flow cat into a 2.25" RS*R Ex-Mag catback exhaust. Only reason I did it this way was because I couldn’t find a header with a 2.25" collector, it’s either 2" or 2.50" from what I’ve noticed.
It’s better to have something smaller flow into something larger than to have something larger try to squeeze into something smaller.
can a header w/ 2" collecter be modified to 2.25??
It can be on headers for American cars, so it probably can be here too. But it probably wont help much, if at all. You could like take the collector off and get another, but the primaries are still the same size, and where they come together, that will still be the same size. You can certainly cut the flange a little short and then weld another flange onto that which will make it 2.25" but again, not much point.
Hey Teckno my car would is similar to yours except i have a thermal catback. How does your car sound w/ the header and carsound cat? Any difference?
It sounds pretty mean, granted that it’s an automatic (manuals always sound better). I have a CAI as well, so you hear a little more engine noise also. Noticable gains in the mid to high RPMs.
Your setup sounds like a reliable and nice set up I might be setting up the same way. The mid range and high range gains sound good for a 5spd. I have a 5spd and auto teg. im selling one of them if you know anyone or interested in it yourself. http://g2ic.com/forums/showthread.php?t=111091
The pipe diameter as per RS-R’s site is 60mm. Now I don’t know if that is ID or OD…should’ve used a caliper to measure the ID of my RSR EXMag when I put it on. But 60mm is more like 2.36"…or 2 & 11/32". Maybe the I.D. is 2.25"
EDIT: WOOPS thought that said January 2006… or forgot that it was 2006. So sorry to dig this up! OOPS! 