hey, i have a 98' 2.4L sunfire, and i have a obx 4-1 header to put on, with a dual cat back exhaust...........listen the downpipe off the header is 2 3/8", and the exhaust piping is 2 1/4"............i am replacing the cat with a high flow one, and i've been told that i should get a 2 1/2" cat, now i thaught cats created some back pressure for your system, which i want with the headers, but i don't really know all that much about cats, so if anyone knows any good solutions of what size cat to get, please let me know....peace

the whole exhaust will create backpressure

its only going to flow as fast as the thinnest part will allow

cool, thanks bud, so i figure i'll go with a 2 1/2" cat, should be nice, thanks...

good luck

id stick with 2.25 all the way with cat, muffler, resonator, or whatever you use in there.
like said above the 2.5 isnt going to help any

and its HEADER no "s"

crazy sig man

yeah if you are staying n/a 2 1/4" will do you fine

if you are giong boosted 2 1/2-3" will work

thanks for the feedback, yeah im plan to keep it n/a until there is need for boost, thanks again. So, have many of you guys replaced the resonator on your rides?, If so, anyone know where to get good quality resonators for the 2.4L engines?.........peace

http://justmagnaflow.com/





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magnaflow 94035 for 2.25

magnaflow 94036 for 2.5

both come with o2 bungs for the o2 sensor already welded in, and shouldnt through a single code.

on a side note this is the size cat rksport sells for our cars.

i run the first one with header

sweet, nice lookin engine bay there red2.zcav....looks good, yeah c, i can get a full stainless, with polished shield for $170 cdn, thats for the 2 1/4" high flow cat, however rksport will sell me theirs for $160 us, plus shipping etc.., now, i am just wondering, how efficient it is to stay with same company, i have the dual cat back from rksport, very pleased when it cam, which has the magnaflow mufflers, should i stay with a magnaflow cat as well, or does it really not matter all that much?....thanks peace.......as soon as i have the exhaust done, i'll post pics of evrything.......got nothin up right now however.........peace

Kyle Anderson wrote:sweet, nice lookin engine bay there red2.zcav....looks good, yeah c, i can get a full stainless, with polished shield for $170 cdn, thats for the 2 1/4" high flow cat, however rksport will sell me theirs for $160 us, plus shipping etc.., now, i am just wondering, how efficient it is to stay with same company, i have the dual cat back from rksport, very pleased when it cam, which has the magnaflow mufflers, should i stay with a magnaflow cat as well, or does it really not matter all that much?....thanks peace.......as soon as i have the exhaust done, i'll post pics of evrything.......got nothin up right now however.........peace

justmagnaflow sells the same exact parts. wholesale. meaning alot less money.

rksport sells magnaflow.

price on the cat there same exact thing is 68$, price at rksport 160.... these are in USD, but convert em to cdn, and i think you will still find the lower price at justmagnaflow.

yeah, even after cdn. conversion and shipping, still will be cheaper than the one from rksport, thanks alot bud, yeah thats where i'll get the cat from, thanks again, i get a good deal through a NAPA parts store here through my school, and still "justmagnaflow" is way cheaper by like $70cdn.....thanks again....peace

with the 94035...will i have to cut the exhaust to make everything fit...or is the cat the same length? thanks

Grillrd wrote:with the 94035...will i have to cut the exhaust to make everything fit...or is the cat the same length? thanks

its universal, so plan on cutting and clamping. if you add a header, then you are gonna cut and clamp anyways. and most catbacks are the same.

theres really no need to change to a high flow cat on an exhaust thats stock from the head to the cat or the catback to the muffler unless the cat is dead.

not to thread jack but event what resonator do you run ?? part number?

thanks



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Sweet, the cat is on it's way.......should be here within 7 seven days, right after it gets here, the header, cat, and exhaust is going on, i'm gonna dyno it after, so i'll post numbers and pics of the setup in a week or so...thanks again for all the help guys........i have another question too........has anyone done the trottle body spacer and intake manifold mod together, does it give decent gains? i know rsm makes both that go with each other, i think it's 62mm or something, yeah wondering how well they perform??......anyway thanks again.....peace

Red2.ZCavi (The Slanky One) wrote:not to thread jack but event what resonator do you run ?? part number?

thanks

http://www.j-body.org/forums/read.php?f=2&i=299375&t=299375&start=0

2/3 down the page, reason i am posting the link cause theres more than one res, not sure which one you wanted, but all parts listed

yeah, i was think of straight piping after the cat, cause i dunno, though, but i have the dual glasspack mufflers, and im thinking that it will still sound pretty good, and then you know if it's terrible then i'll put one in, i have an intake too on it, so any advice would be appreciated though?...........peace

i;d use a muffler, but thats just me. i dont like tickets, or ungodly loud cars...

yeah, thyats what i meant, sorry, i have two of the magnaflow mufflers with the 4" tips, i figure i can just use them instead of a resonator, and just straight pipe from cat back to mufflers????? what you think?, the piping i have is all ferritic stainless 2/14", so i think it'd be nice to just pipe instead of the resonator..........and yeah, up here in alberta, you dont have to worry about emissions, only Ontario.......peace

you can try it, but two mufflers as in dual exhaust... prob not gonna sound the greatest hence the need for a resonator. unless you planned to have one outlet, but use two mufflers inline (hard to fit possibly.)