stock wrx exhaust size

[legacy98gt]

hey someone locally has a stock wrx exhaust from a 04 wrx for 50 bucks obo, i was wondering wat size piping is it? i heard it will work with a little modification and i now how to weld but how much modification just the mounts?, i was goin to offer 40 and replace the muffler with a spin tech muffler but my spin tech is 2 1/4 just wondering if it will work thanks

[rougeben83]

viewtopic.php?f=11&t=10919 (https://sl-i.net/FORUM/viewtopic.php?f=11&t=10919)

[subie/legacy]

I have a stock catback in my shed from an 04 wrx and it has the dual tip design...
and the piping size is 2.5" if I remember correctly. I could always walk out there and snap a pic if you like.

[ouch1011]

As rougeben said, STI exhaust is only about 2 1/4". So WRX is probably close to 2"

Stock Legacy exhaust is about 1 7/8"

[99gtlimited]

I have an 07 wrx muffler on my car and I measure it at 2.165" OD which is 55mm, the STI is 60mm which is about 2.3"

[subie/legacy]

I must be measuring wrong, but I'm getting very close to 2.5" on my 04 wrx piping. well more like 2.3/8"
went out and snapped a quick pic, sorry about the low quality cell pics

http://i631.photobucket.com/albums/uu33/mickereghan/Mobile%20Uploads/IMG00278.jpg?t=1277212963
http://i631.photobucket.com/albums/uu33/mickereghan/Mobile%20Uploads/IMG00279.jpg?t=1277212963

[Sarra]

As a general rule of thumb, NA exhaust is 2.25" for 2.5 liter, 2" or smaller for 2.2 liter and smaller, 2.0 WRX is 2.5", and STI exhaust was either 2.75" or 3", though I don't pay much attention to that. For all I know it could be 2.5" like the WRX.

[99gtlimited]

Again,

OEM sizes are 55mm for '07 WRX (which uses a 2.5L) and 60mm for STI.

If you convert these numbers you get
55mm = 2.165"
60mm = 2.362"

I have confirmed this for the 07 WRX Axleback, measuring ~2.17" OD on the pipe itself (shouldn't be measuring at the flange) using a dial caliper.

The older WRX piping would not be larger than the 07 since it would be from a 2.0L, so you're 2.5" diameter is incorrect. Try using a caliper or micrometer to measure the tube somewhere not at the flange and get a better reading.

This has already been covered in previous threads, so if no new information is added, this thread is somewhat useless (and up until now, incorrect)

[subie/legacy]

ok. thank you. that kinda makes me happy. I really didn't want that large of piping.

[ouch1011]

I would say 2.25" on an N/A EJ25 would actually be over-kill since these are not high RPM engines. 2" would be fine unless it is pretty freaking modified.

That being said, I'm going with 2.25", because the selection of mufflers is better for 2.25" than 2".

[rougeben83]

I guess its safe to say no one even bothered to click the very first reply in this redundant thread.

here ya go buddy!


I think this was covered here before, that the 04+ WRX's shared the same exhaust as the STi's sans the pretty tip...

Actually that's not quite correct;

https://sl-i.net/FORUM/images/imported/2008/09/P1060778-1.jpg

https://sl-i.net/FORUM/images/imported/2008/09/P1060787-1.jpg

The first pic shows an 06 WRX axleback, as you can see, the STi piping (the cut flange section) is bigger. How much bigger? The WRX is around 2.16" (55mm), the STi is around 2.3" (60mm). The tips are also different, with the STi having slightly bigger inner diameter. Finally, I think the STi has less baffles than the WRX, it's a louder, lower, and more raw (more metallic) sound than the WRX. I ran both of these mufflers on a 2.5" exhaust without any resonator.

What does that mean to you guys thinking about using these mufflers? Basically, what exhaust piping and possible expectations you should see with either one. The WRX is better suited to be mated to a 2.25" pipe, and will probably sound more civilized on an NA subaru (keep in mind turbos are like mufflers in terms of quelling exhaust noise). The STi muffler would be better mated to a 2.5" pipe, or if you desire a louder more aggressive exhaust tone; it will also be louder than on any turbo Subaru that has this same muffler (keep note of this when you listen to exhausts). The STi muffler will need a bigger resonator than the WRX muffler to keep the rasp/raw sound down.

Either one is a great value IMO.

Exhaust clips to follow.