wrx and sti exhaust

[mr_g]

Debating on buying a wrx or sti axleback. Does anyone have either a wrx or sti axleback that's connected to a stock midpipe? I seen some on here but they use a custom midpipe? What are the differences between a wrx and sti axleback? I read that it requires cutting and welding flange and hanger correct?

[r3v_v3ng3]

I think the difference between the wrx and sti axleback is that the sti have larger diameter piping. They should be the same bend. Yes it requires cutting/welding

[mr_g]

Do they have different size tips too? I looked at some pictures on the web and it seems some wrx have dual tips?

[r3v_v3ng3]

yup, different tips. wrx=dual ; sti=single

[rougeben83]

wrx's of 02-03 have dual tips, 04-07 have single. The piping is bigger on the sti vs. the wrx as well. I think I have a comparison pic somewhere here. It's like 1/4in (5mm) bigger or so.

[Sub-Goon]

Will a STI axle back net the nice boxxer sound? Maybe less volume than a STI, since its not turbo?

[1996Battlewagon]

Will a STI axle back net the nice boxxer sound? Maybe less volume than a STI, since its not turbo?

By itself? No. The "Boxer Rumble" is what happens when a flat four fires in an odd firing order through, and here's the kicker, un equal length headers.

Those are the key. WRXs and STis have them from the factory.

[Sub-Goon]

Will a STI axle back net the nice boxxer sound? Maybe less volume than a STI, since its not turbo?

By itself? No. The "Boxer Rumble" is what happens when a flat four fires in an odd firing order through, and here's the kicker, un equal length headers.

Those are the key. WRXs and STis have them from the factory.

Damn! I was afraid of that! I'm hoping to keep myself clear of getting too deep into a car, got enough time and money and grins with my motos!

[Wiscon_Mark]

The STi muffler is much louder than the WRX muffler. It will give you more rumble, but also more drone. UEL headers will enhance that low rumble and make it deeper.

[nff]

Will a STI axle back net the nice boxxer sound? Maybe less volume than a STI, since its not turbo?

actually a NA engine will always be louder than a turbo engine. turbo's are essentially a muffler

[Wiscon_Mark]

Yep, sound doesn't travel through a turbine like it travels through regular air. I was unpleasantly surprised by how loud the STi muffler was on my Outback.

[unsullied_spy]

Yep, sound doesn't travel through a turbine like it travels through regular air. I was unpleasantly surprised by how loud the STi muffler was on my Outback.
Stock exhaust on an STi is actually fairly loud. On an N/A engine I'd bet you'd be happier with the sound and performance of the stock exhaust vs. STi

[Wiscon_Mark]

I think you lost me with that sentence.

I have ridden in and heard STis from outside the car under acceleration. Yes, they are louder than your average car, but not so much that you get horrible cabin drone like I had with my STi muffler. As Huffer has pointed out, the combination of that and the hi-flow cat I had wasn't a very good one. With stock cats, it may not have been as bad.

[kanner95bk]

I've got an STi muffler on my 95, and yes I had to do a custom mid pipe. It sounds much better than stock, even though it's not a whole lot louder. The tone is lower, and when on the throttle it sounds meaner than stock, and yes a little more rumble. The cabin drone isn't bad at all, you can hardly hear the exhaust even over the radio. I like it because it sounds great but isn't obnoxious.

[pleaidestar]

Doesn't the bigger diameter mess with the motors back pressure? I was going to put an 06 wrx axleback on my sedan and was told it may trap the heat and burn exhaust valves after time. I didn't do it but also thougt the rest of the piping is stock diameter so it may not matter.

[grayguy]

^Idk who told you that but I wouldn't take any more advice from them.

[Wiscon_Mark]

Well, if you go way too high of a diameter, yes, the lack of flow can cause the exhaust gasses to cool off and slow down a bit in the exhaust.

But we're talking a lot larger than 2.25" on a N/A engine.

The valve burning problem I've heard of from the opposite - too much flow (aka straight pipes) but I'm not sure how true that is.

[unsullied_spy]

Well, if you go way too high of a diameter, yes, the lack of flow can cause the exhaust gasses to cool off and slow down a bit in the exhaust.

But we're talking a lot larger than 2.25" on a N/A engine.

The valve burning problem I've heard of from the opposite - too much flow (aka straight pipes) but I'm not sure how true that is.
Valve burning is a result of hot exhaust valves cooling too quickly. Ever see those monstrous v8 power boats with the pipes going straight up off of the heads? They have to put socks (or, commonly, tennis balls) over those to keep the valves from cooling too quickly which will shrivel them up. Same concept here but I don't know what it takes to do that with a car exhaust...

[Grimmrican]

Yeaaaaaa stupid noob me we t with a 3" cat back. I have already come to the conclusion of going down to 2.5 or 2.25". I notice my car is louder but lack power :/ wish I was thinking right when I did this

[pleaidestar]

I had heard the same about mid pipes being too big (and straight), I don't recall where I heard the bs about the muffler doing that to the valves...probably the internet;). I questioned it even though I more or less make air flow work better for the industry I'm in.

[unsullied_spy]

I had heard the same about mid pipes being too big (and straight), I don't recall where I heard the bs about the muffler doing that to the valves...probably the internet;). I questioned it even though I more or less make air flow work better for the industry I'm in.
Too big of a pipe and you don't get enough back pressure, something to do with a scavenging effect but I'm no expert. I know the valve shriveling is true for boats but those engines typically get hotter and are directly exposed to cool air--a car exhaust isn't nearly as severe. I was told by a Subaru mechanic that the turbo ones tend to burn exhaust valves but I don't remember what reason he gave.

[86bratman]

A 2.25" exhaust is a fairly common upgrade on 4 cyl's, it will not cause any engine damage. For best results go with a full 2.25" exhaust on your car, or at least from the cats back.

[kTri]

Hi, I want to get clarification about exhaust upgrades on a N/A 2.5. What is the best way to get overall quality(sound, performance, set-up, rumble, etc) and also safe(not falsely effecting anything else on the car) on the car?

I have an 02 Legacy L 2.5 that I may consider eventually doing exhaust work to. How would you go about doing so?

[1996Battlewagon]

Safe and sound would be a basic 2.25" cat-back with headers. You won't throw any CELs that way and it will be relatively quiet depending on what muffler you pair it with. Well, sort of. I got a noise violation citation on the interstate with mine.

Check this thread out.

viewtopic.php?f=11&t=26411 (https://sl-i.net/FORUM/viewtopic.php?f=11&t=26411)

[kTri]

Safe and sound would be a basic 2.25" cat-back with headers. You won't throw any CELs that way and it will be relatively quiet depending on what muffler you pair it with. Well, sort of. I got a noise violation citation on the interstate with mine.

Check this thread out.

https://sl-i.net/FORUM/viewtopic.php?f=11&t=26411

Thanks for the pointer o think that sums up the do's through this whole thread and not the dont's of it. I even saw the clip that you thought was a solid set-up. Everything was listed the way you explained.

[d1giPhux]

I am running the subaru SPT bosal exhaust on my 99 LGT. The piping is 2.25" i'm pretty sure. Also running 2.25" midpipe. I'm pretty sure this was the stock piping on this car. Either that or .25" bigger. Either way, it has a nice tone, even able to get loud at WOT, but also does not slow you down from being too large of a pipe.

Ive had large pipes on other cars (honda) before and they suck because you bog down (with NA) and dont build torque as fast it seems. I chose to run the 2.25" on this car and its great. Running stock cat as well.

[kTri]

I am running the subaru SPT bosal exhaust on my 99 LGT. The piping is 2.25" i'm pretty sure. Also running 2.25" midpipe. I'm pretty sure this was the stock piping on this car. Either that or .25" bigger. Either way, it has a nice tone, even able to get loud at WOT, but also does not slow you down from being too large of a pipe.

Ive had large pipes on other cars (honda) before and they suck because you bog down (with NA) and dont build torque as fast it seems. I chose to run the 2.25" on this car and its great. Running stock cat as well.

What about headers. That stock too?