[geoff1]

I have an 07 STI that is almost completely stock. I have been running it very successfully at a regional level in STU. Next season I would like to attend some PRO or National events and I plan on modding my car to make it more competitive. I know there are a lot of threads out there about the new emissions rules in this class, but I am still a little confused.

First of all, how are these rules enforced at these national/pro events? Do they actually hook a scanner up to your OBD-II port to determine if you are test ready with no CEL defeats or is it honor system like a regional event?

My second question is about the COBB catted downpipe. I plan on buying this downpipe, but I want to make sure it will be legal. I read that last year's champion STI had this DP on it, but ended up switching it to a Perrin DP because the cat wasn't heating effectively enough to not throw a CEL. Is anyone able to run this DP successfully and legally in STU? Cobb has STU maps published for it for 04-06 STIs and a BETA map for the 07 STI. Is anyone running these maps?

Thanks in advance for any help.

[Jesse]

you can NOT run a DP in STU.

you would be in BSP.

this is from my understanding... the experts will chime in though.

[geoff1]

Originally Posted by Szumita

you can NOT run a DP in STU.

you would be in BSP.

this is from my understanding... the experts will chime in though.

You can run a downpipe as long as it has at least one cat that not too far downstream. I know that physically the Cobb catted DP is perfectly legal in STU. My question was about being able to not throw a CEL with this DP and the effectiveness of Cobb's STU maps.

[IlliniSTi]

Originally Posted by Szumita

you can NOT run a DP in STU.

you would be in BSP.

this is from my understanding... the experts will chime in though.

And your understanding is wrong. In STU headers, uppipe, downpipe and catback are all legal. The key thing is to retain one cat within a specified distance from where the originals were. The cobb DP does that.

Originally Posted by geoff1

You can run a downpipe as long as it has at least one cat that not too far downstream. I know that physically the Cobb catted DP is perfectly legal in STU. My question was about being able to not throw a CEL with this DP and the effectiveness of Cobb's STU maps.

Now there are two tricky issues with any exhaust mod in STU. First is emissions legality. This rule is fairly silly IMO, but it's what you have to do. You may run the stock map with the DP and as long as you do not throw a CEL and are in ready state, you are legal. You can also get a custom tune which does not alter the boost table and does not turn off any CEL codes. Again ready state and no codes equals legal. I have the cobb DP and ran for a while in both situations. I did not get a CEL in either case.

The second thing is the heatshield. The latest fastrack "clarified" that the heatshield that covers the downpipe was not an "exhaust" heat shield, and therefore not able to be modified. However, this did create a large amount of feedback, and may be reversed. We can only hope, and write letters.

As far as at pros, tours, and nationals, at the milwaukee tour no one scanned anything. I don't know if they did anything at Nationals this year. My guess was no.

So my advice is that the cobb dp with the high flow cat should be OK for STU, but I also recommend getting a custom tune for it.

Also, the autox thread on nasioc is a good resource for these types of questions.

[geoff1]

Originally Posted by IlliniSTi

And your understanding is wrong. In STU headers, uppipe, downpipe and catback are all legal. The key thing is to retain one cat within a specified distance from where the originals were. The cobb DP does that.



Now there are two tricky issues with any exhaust mod in STU. First is emissions legality. This rule is fairly silly IMO, but it's what you have to do. You may run the stock map with the DP and as long as you do not throw a CEL and are in ready state, you are legal. You can also get a custom tune which does not alter the boost table and does not turn off any CEL codes. Again ready state and no codes equals legal. I have the cobb DP and ran for a while in both situations. I did not get a CEL in either case.

The second thing is the heatshield. The latest fastrack "clarified" that the heatshield that covers the downpipe was not an "exhaust" heat shield, and therefore not able to be modified. However, this did create a large amount of feedback, and may be reversed. We can only hope, and write letters.

As far as at pros, tours, and nationals, at the milwaukee tour no one scanned anything. I don't know if they did anything at Nationals this year. My guess was no.

So my advice is that the cobb dp with the high flow cat should be OK for STU, but I also recommend getting a custom tune for it.

Also, the autox thread on nasioc is a good resource for these types of questions.

Thanks for the response. The whole heatshield thing seems pretty frustrating. I'm guessing that pretty much every aftermarket dp requires some trimming of this shield. I do plan on getting a custom tune for the dp. I just wanted to make sure this would be a dp that wouldn't throw a CEL even with a tune. I read in another thread that last year's winner switched to a perrin dp because the cat on his Cobb dp "wasn't heating effectively" and would throw a CEL. I like the design of the Cobb pipe better and would prefer to get it though. Maybe I need to wait and see how the heatshield clarification plays out. Do you have any idea when that will be? Did this all happen recently?

[IlliniSTi]

Originally Posted by geoff1

Thanks for the response. The whole heatshield thing seems pretty frustrating. I'm guessing that pretty much every aftermarket dp requires some trimming of this shield. I do plan on getting a custom tune for the dp. I just wanted to make sure this would be a dp that wouldn't throw a CEL even with a tune. I read in another thread that last year's winner switched to a perrin dp because the cat on his Cobb dp "wasn't heating effectively" and would throw a CEL. I like the design of the Cobb pipe better and would prefer to get it though. Maybe I need to wait and see how the heatshield clarification plays out. Do you have any idea when that will be? Did this all happen recently?

I suspect something will be in the next fastrack. I'm not sure when it is due out, but probably won't be until after run-offs are done. Check SCCA.com for it. The heat shield thing is very recent. It was in the last fastrack that was published. If you are an SCCA member you can write to seb@scca.com and tell them you think it's a bad idea. Make sure to include your member number.

[geoff1]

Originally Posted by IlliniSTi

I suspect something will be in the next fastrack. I'm not sure when it is due out, but probably won't be until after run-offs are done. Check SCCA.com for it. The heat shield thing is very recent. It was in the last fastrack that was published. If you are an SCCA member you can write to seb@scca.com and tell them you think it's a bad idea. Make sure to include your member number.

I wrote them today. Here is my letter:


I am writing to tell you that I think the turbo/exhaust heat shield clarification for Subarus is a bad idea. My car has the stock exhaust and heat shield on it right now, but I am planning on changing my downpipe to and aftermarket pipe which would require trimming the heat shield. When I joined the SCCA to compete in STU I assumed this would not be a problem since all of the Subaru STIs and WRXs competing in this class on a national level have trimmed heat shields. The rules also state that trimming an exhaust heat shield is legal.

The heat shield in question is designed to cover the bellmouth or front section of the downpipe which is an *exhaust* component. This should make trimming the shield perfectly legal. There is also no performance advantage gained by trimming this heat shield, and trimming it does not affect the turbo in anyway.

Letting this clarification stand will not lower the performance of the Subarus competing in ST classes. It will just make it more expensive for Subaru owners to compete in these classes. Instead of being able to buy off the shelf downpipes at a reasonable price they will be forced to make custom parts that adhere to the new rules. This is very discouraging to a person like me who got into STU because I could be competitive without spending a lot of money. I know one membership probably doesn't mean much to you guys, but if this clarification stands I will likely not be renewing mine.