[supermarkus]

When we initially read this post it was under the assumption that MOP removed the stock pipe, gutted it, then went to dyno it. If he did it in that order, he may have disconnected the battery. Why not ask MOP what the exact conditions were instead of playing the guessing game? Maybe someone with lots of time on their hands and a delta dash can repeat the experiment. N=1 isn't exactly good science. This would be a great experiment for bored STi owners

I bumped this thread to start some discussion on the subject of aftermarket up-pipes after I read on NASIOC that some guy was basically saying "bigger is better" with up-pipes and that an aftermarket pipe CLEARLY will outperform an STi pipe.

 

[Big Sky WRX]

If there is evidence of aftermarket uppipes clearly outperforming the STi's I'd love to see that, although I certainly won't be holding my breath.

Big Sky

 

[ScstealthVR6]

what does gutting an uppipe consist of? can you do it yourself? what kind of shops do this, exhaust or tuners? is the price of getting the work done that much less than an aftermarket uppipe? and it seems many people are concerned about smog problems so buying an aftermarket uuppipe and being able to switch them for smog check makes sense.

 

[Big Sky WRX]

Yes you can do this yourself- most people opt on getting a second one used, then do the work at there leisure. After installing it you can sell the one on your car for the same price.

The uppipe is a precat- it's sole purpose is for cold start emissions- once th4e car is near operating temps it isn't doing much in the way of "smog" control.

An uppipe isn't something you just put in/take out when needed- once you do one you'll understand.

I've seen pregutted uppipes for sale occasionaly. The advantage of an oem uppipe is price, fitment and the "stealth" look. Aftermarket pipes cost more, but perform slightly better.

Big Sky

 

[supermarkus]

Aftermarket pipes cost more, but perform slightly better.

Big Sky

Care to qualify that? Numbers?

 

[qoncept]

Care to qualify that? Numbers?

Look at the first post in this thread.
0.

 

[supermarkus]

Look at the first post in this thread.
0.

Did you? It said that the gutted stocker performs better by a foot pound and has a higher trap, Big Sky was saying an aftermarket performs better.

 

[Big Sky WRX]

What I get out of this thread is the gutted stocker performs very well- makes sense your removing a restrictive cat. I think it will perform very close to aftermarket uppipes (and as mentioned cheaper, good fit and stealth). But IMO aftermarket pipes don't have the slight change in diameters like the stocker (it's not it's fault it was designed that way to house a cat) and will perform slightly better- the key word is slightly.

Measurably it would be tough to tell as your not talking a lot of difference. You could do lots of dyno runs and lots of 1320's and it would likely go back and forth and be very close, reinforcing the pieces will perform very closely. If you had perfect laboratory conditions I think the aftermarket (maybe not all due to different designs?) pipes would prove slightly advantageous.

I don't get out of this thread the gutted stocker is the best uppipe, I get it works really well and you can't beat the price.

Big Sky

 

[supermarkus]

I see where you're coming from.

 

[subadu]

Ok i know this is an old thread but after reading this, it should be part of a "modding 101" very informative i must say. If you gut your stock uppipe will you still pass emmssions? And is thist somthing you could perform in your garage? basic tools, and floor jack?

thanks

 

[mateusz h2o]

Ok i know this is an old thread but after reading this, it should be part of a "modding 101" very informative i must say. If you gut your stock uppipe will you still pass emmssions? And is thist somthing you could perform in your garage? basic tools, and floor jack?

thanks

wow this is an old thread but no one responded to this guys question so here it is

as stated above yes it will pass smog the upper cat is just for cold starts, once the car is warmed up and running the upper cat is basically useless, so when you drive to get the car smogged by the time you get to the shop your car should be warmed up and in that case the gutted u/p is safe.

and if you can do it yourself yes you can here is the link.

http://webpages.charter.net/baraboo_halls/auto/wrx/up/uppipe_fix.html

but like others said its easier to buy a used u/p gut that one at your leasure then replace your u/p with the one you gutted and sell yours.

 

[Big Sky WRX]

I'm going w/ this option as the SCCA gas changed things up in allowances for exhaust. The consider the egt probe part of the emissions system and has to be in (even though they do allow the cat to be removed!), my STi uppipe has no provision for the probe, so I'm going to gut the stocker. 99% of the time (except at events) I'll run in sans probe (w/ resisitor fix).

 

[mateusz h2o]

I'm going w/ this option as the SCCA gas changed things up in allowances for exhaust. The consider the egt probe part of the emissions system and has to be in (even though they do allow the cat to be removed!), my STi uppipe has no provision for the probe, so I'm going to gut the stocker. 99% of the time (except at events) I'll run in sans probe (w/ resisitor fix).

can you say that in laymans terms please(newbie)

thanks

 

[302@12psi]

I'm going w/ this option as the SCCA gas changed things up in allowances for exhaust. The consider the egt probe part of the emissions system and has to be in (even though they do allow the cat to be removed!), my STi uppipe has no provision for the probe, so I'm going to gut the stocker. 99% of the time (except at events) I'll run in sans probe (w/ resisitor fix).

Wont it throw a code de-catted with the stock EGT in there?

 

[Big Sky WRX]

there was a "clarification" dealing w/ STX autox class, pretty complex and quite frankly I don't think a lot of folks completely understand all of the ramifications. In regards to the oe uppipe there is a egt probe, the probe they )SCCA) has deemed part of the oe emissions system that can't be removed (or fooled)- thus the need for an uppipe w/ the bung for the probe (some aftermarket uppipes incluse this).

^ evidently not. At the 2007 Nationals no one reported any cel problems w/ the egt probe. It's possible if this is driven day in and day w/ the probe (and no cat) you might get one, but at least short term it appears it doesn't throw one. I'll remove it when not an event simply because the risk of the probe breaking up and hurting the turbo

 

[plac]

ohhhh, ok.....i read it wrong.....when you wrote "Stock uppipe -cat
" i took that as, your stock up-pipe, WITH the cat....but i guess you meant, the stock up-pipe MINUS the cat.....

ya i saw it that way too... now it makes more sense..

 

[Big Sky WRX]

my long bit and extension came yesterday, this weekend I should have it gutted

 

[Micah]

there was a "clarification" dealing w/ STX autox class, pretty complex and quite frankly I don't think a lot of folks completely understand all of the ramifications. In regards to the oe uppipe there is a egt probe, the probe they )SCCA) has deemed part of the oe emissions system that can't be removed (or fooled)- thus the need for an uppipe w/ the bung for the probe (some aftermarket uppipes incluse this).

^ evidently not. At the 2007 Nationals no one reported any cel problems w/ the egt probe. It's possible if this is driven day in and day w/ the probe (and no cat) you might get one, but at least short term it appears it doesn't throw one. I'll remove it when not an event simply because the risk of the probe breaking up and hurting the turbo

Any rule that says you can't mount the EGT probe in these threaded into the same spot?

 

[Big Sky WRX]

unfortunately yes- any addition of a "mechanical", electrical or ECU "fix" is not allowed- used to be fine, but since the "clarification" no longer so- grrrr

 

[plac]

I just ordered the Invida uppipe with both gaskets and downpipe top gasket. I was going to order Cobb and stick with my theme, but i saw so many good reviews of Invidia I had to get it. Its also almost $100 cheaper than Cobb..