question regarding headers!

[v10kingsnake]

i have a 97 gts with a borla catback (older stlye) and i recently got rid of the cats too! question is, if i remember correctly the inlet into the cat, when it was there was 2.5" but i know i want to go headers and forced induction, roe blower very soon, so how is this done. will i have to just bolt up the new headers with the 3" pipe then reduce it to fitinto the borla cat-back which i believe runs out the back 3" again. please help guys. -kingsnake

 

[Simms]

My B&B headers are 1 3/4" primaries, into a 3" collector. The collector bolts to a 3" elbow (for lack of better words) which then connects to cats or no cats. I imagine all you would need is a reducer from the 3" piece to the 2.5" pipe you replaced your cats with.

If you already have a 3" catback, just use a 3" pipe to connect your headers to the cat back setup.

 

[Torquemonster]

Why keep 2.5" cats if you are going to run boost?

Boost likes to get the gas out, not constipate itself thru a straw. There are several options for 3" cats - I'd do that and keep the system flowing free unless noise reduction is more important than power.... in which case run 2.5" all the way out back from the cat. It'll drop considerable top end power, but will still be a lot better thanstock, but noise will be a lot less with 2.5" system than a 3".

If comparing options on a 3" - the thicker the guage the quieter. A thin guage will resonate and have an annoying shrill note... even more so re mufflers

 

[v10kingsnake]

torguemonster, you need to read more carefully as i do not have CATS, bro. my exhaust IS a 3 inch cat back but it is designed to slip fit onto where my stock cat exits being only 2.5" so the end flowing in the borla muffler is 2.5 and out the muffler for the remainder of the system is 3" i would hate to replace my borla mufflers just because of this so i think a reducer is the best way to go. not too sure the performance will be hurt by this funnel either. what do you think, surely someone here has already been through what i am thinking!

 

[Torquemonster]

Keep the 2.5" diameter to a minimal lenght but make the transition as much of that as possible... i.e. a cone = the best way to reduce rather than a sudden drop which will cause turbulence...

to find a 3" into 2.5" cone reducer - you might need to shop around

 

[Simms]

Are you sure your Borla setup doesn't have a 2 1/2" to 3" adapter before the muffler? My B&B catback had this incase you were using stock converters, it is removed if you are using 3".

 

[FE 065]

i have a 97 gts with a borla catback (older stlye) and i recently got rid of the cats too! question is, if i remember correctly the inlet into the cat, when it was there was 2.5" but i know i want to go headers and forced induction, roe blower very soon, so how is this done. will i have to just bolt up the new headers with the 3" pipe then reduce it to fitinto the borla cat-back which i believe runs out the back 3" again. please help guys. -kingsnake

You don't need any reducers. The inlet hole (and core) on the Borla muffler is 3" (or very near it) at the muffler case weld. Most of, but not all of the spigot in front of it is reduced to 2.5". You might be able to just have a muffler shop expand the rest of the spigot to 3" or near that (I don't think they can open it up that much though) or cut the 2.5" part off and weld a 3" spigot up to the short 3" piece that'll be left sticking out the front of the muffler.




Anyone needing reducers can get them from Burns Stainless, Headers by Ed and Burns Stainless sell quite a selection of megaphones as well.

 

[cgmaster]

I also have the old Mopar borla setup. I cut the reducers off and welded a 3" section to the inlets on the mufflers. Hope this helps

 

[99 R/T 10]

I think everybody needs to get themselves a set of B&B headers! I just happen to have a set in the classifieds