Finally going stage 2 (serious this time!) on my 06 WRX. A friend of mine has the tools and the experience (not with Subies though...), so we got a time setup in a couple weeks to get this done. I currently have the SPT catback installed, and I'm going to throw a Cobb catted downpipe in there. I bought it from someone here and I don't have any of the additional hardware that would have come with it new. My friend who's helping told me to "Just bring all new bolts and gaskets and we'll get it installed." I also plan to buy a new turbo heat shield, but my question is, do I need to get all new bolts (for the turbo to dp and the dp to catback)? If so, what are the specs on the bolts that I'd be replacing and can I find them locally, or would online be my best bet? Same questions goes for the gaskets. I'm assuming that since all these pieces fit the same as stock, that I'd be using bolts/gaskets that would match the stock specs. Sorry guys I'm clueless on this stuff! Any other words of wisdom before we get started on this install? Any advice would be much appreciated! Jeff
get the gaskets from the dealership. chances are your original bolts/nuts/studs can be re-used. The dealership can get those as well if you want/need new ones. If you're in a pinch, a good Ace Hardware or NAPA will have the correct size metric hardware.
I just did my downpipe install last week. When I did my catback, I snapped both bolts that connect it to the DP. So i would just plan on replacing those. I reused the turbo to DP gasket and all of the bolts/nuts on the turbo/DP connection. If you go this route, just make sure that the gasket isn't cracked or disintegrating or anything. Most likely the gasket for the DP/CBE connection will be destroyed. I also snapped 3/5 bolts for the heatshield, so be prepared for that lol. ACE Hardware is probably going to be your best bet for bolts, just bring the old ones in and match them up.
I was able to swap my cat back and my downpipe once each while keeping the DP to CBE bolts in working order. The third time undoing these bolts, the spring loaded bolts snapped off. If you are going to be using the OEM-style donut gasket between the downpipe and the cat back, then you should be using OEM spring loaded bolts. These are made to allow flex at this joint (the whole point of the donut gasket). If you switch to a flat gasket then you have to switch to normal bolts to get it to seal. For the downpipe to turbo you might be able to re-use the gasket, but I tried this and ended up finding out that I had a leak when I went to swap the downpipe again a few months later. A new OEM gasket is recommended. Or get the extra thick one from GrimmSpeed.
Tips from my install: Remove the Intercooler (takes like 10 minutes and gives you a whole lot more room to work) The sensor in the DP can be unplugged if you cant unscrew it while its under the car. And as a general rule, always allow double the time you think it will take.
I should have mentioned that I have an AP ready to go (already flashed it Stage 1 a couple years back) - so I'll use that for a little while, then likely do a custom tune. Thanks for all the info/advice - you guys are awesome - since I'll have someone helping me I'll likely just plan for anything that could go wrong so I don't take up his whole Saturday! Jeff
One thing to think about. Now you will have a 3" DP going to a SPT Catback. The SPT exhaust says it is 3" but when you look at the midpipe you will see that this is not true. So you will be putting a larger DP pipe on a smaller SPT midpipe, back to a 3" axleback pipe. I did this and ended up with some exhaust leaks in my system. Even if you are lucky enough to have flanges that meet up nicely (I did have this) and don't get an exhaust leak right away, you will have a change/disturbance in the air flow where the midpipe choke is. I didn't have a leak right away but my leak happened over time and I think this choke point and disrupted air flow helped form the leak. The failure point was @ my gasket going from the DP to SPT CBE. You could see the black residue on the exhaust from where the gasket was no longer sealing where the flanges met. To improve this setup without buying a new exhaust I would suggest an exhaust adapter. GrimmSpeed has a very nice one, this is what I currently use. NASIOC Product Review 3Gwrx Product Review
Thanks for the heads up - I'm pretty sure that the Cobb DP mates to stock, and the SPT CBE mates up to the stock DP, so I think I should be OK...but I might go measure it just to be sure. The least amount of surprises the day of, the better I figure.
Yeah they will mate to stock that is not the issue here. You are going from a 3" pipe to a smaller midpipe. The SPT midpipe is not 3". The adapter makes the transition from big pipe to smaller pipe smooth. This helps the air flow and reduces your chances of having exhaust leaks.
Also, from what I remember about my 06 STI the SPT catback was 3" all the way. If I recall the early production runs were 2.5 but they changed to 3. So the real issue will be having a 3" DP that tappers to 2.5" and mates to a 3" intermediate pipe. You wouldn't have any more problems with leaks with the Cobb DP compared to stock as they both are 2.5" and accept the donut. The real issue is you have a 2.5" restriction in your otherwise 3" system.
This is correct. The COBB essentially has the GrimmSpeed adapter welded on already. If you're sticking to an OEM cat back, then the COBB is a better choice than a 3" downpipe and the GrimmSpeed adapter.
Thanks for the advice everyone - got this all done today and everything fit perfectly. It wasn't too bad, ended up not taking off the intercooler - and had to heat a few bolts up to get them loose, but all this advice came in handy, replaced the gaskets and the spring bolts. I'm enjoying the heck out of Stage2, wish I would have done it years ago, but at the same time maybe it's better I didn't - I feel like this is a gateway mod, got me thinking about the next one already! Thanks again everyone!
