I have a 94 gsr and i need to get a new header. the gasket between the downpipe and manifold on the stock one is gone and leaks exhaust into my car. Im seeing this as an opportunity to upgrade basically.

My questions are about the collector size. Most headers seem to be 2.5 inches and im pretty sure that doesnt match up to the stock cat. What headers are out there that will bolt directly up to my stock cat (i dont know what size or brand)? Should i just upgrade my cat and the rest of the exhaust too? I know that 94-99 gsr exhaust sizes are different than 00-01gsr/94-01ls/gs/rs.

any input is greatly appreciated!

 

The inside diameter doesn't matter when hooking up if you dont care about losing the power going from big to small. What matters is the flange size. Im 99 percent sure that most aftermarket headers have the same flange type and the stock.

 

okay cool! thanks man. So bolting up a 2.5" header to my stock cat will still fit. Eventually i will get a bigger exhaust, i just need to do it in stages (money wise).

 

IDK about the flanges, but a lot of "name brand" budget headers have collectors designed for stock exhausts (e.g. DC). However the discovery that bigger really is better with catback diameter + the availability of a lot of 2.5" knockoffs has led to 2.5" headers becoming much more common.

Long term you're definitely better off with a 2.5" header, but you're not really going to be seeing many advantages as long as it's routed through a stock cat and stock catback.

You might want to consider having a muffler shop fab you a taper, too, as that will flow better than trying to mate a 1.92" (or w/e) flange with a 2.5"

 

appreciate the input.

 

If the donut gasket is what you are referring to, then take a ride to a local Honda dealer and pick up an s2000 donut gasket. They are 2.5 inch and would be perfect.

Part number:
18229-PCX-003
That's what I did when I wanted to match my T1R header to my catalytic converter. Fit like a glove with OEM quality.

 

thanks man. so i 2.5" collector with s2k donut gasket to stock gsr cat would work?

 

^^ Correct.

 

I was wondering the samething since I need a header on my gsr and I just put a brand new cat on it 2 months ago. Looks like I'm gonna pick me one up soon.