So I have a 2008 GSR X. It has a cai, greddy type s bov, and a Cobb AP. I went over a pot hole and my stock muffler got dented and cracked. Well it's been rattling so I took it off and I'm getting an axle back tomorrow to save money. It's been of for two days and I must admit it sounds pretty nice, I pointed it to the side and down so it does minimal damage, but I got bored put my AP on perrin stage 2, (old owner had it on there), and I just drove. Well I got on it in first at a stoplight and my boost gauge which is my AP went to 33.4 I have pics If needed, i then heard a loud pop and immediately let off the gas, I think it over loaded somthing? But I'm afraid of trying it again. Can my stock turbo boost to 33? Or could I of gotten a used Evo with a different turbo? And also with the muffler off I feel like I've gained a few horses anyone else ever try it?

 

I thought the stock turbo was good to about 26 psi and so 33 seems high. Possible that the boost was just up that high for a second. I'd be surprised if a Cobb AP stage 2 tune would be set for 33 psi, but smarter guys than I will know these things and surely comment. I do know that over boosting can be quite bad - you can go lean, head gaskets go, detonation, broken pistons, all sorts of things.

Not sure what the "pop" sound was...how does the car run now? Does it idle, rev normally, is there a big puddle of oil underneath...? more perspective would help.

As for the muffler. There's been plenty of dyno pulls to confirm that removing the stock muffler, but keeping the rest of the stock exhaust, will not materially increase HP. The difference you are noticing is likely just your driving style. You push the pedal, it's noisy and exciting, and so you push it harder than you might normally and the car feels faster. People notice the same thing when they fill the tank. Now, if you are interested, I can sell you some stickers that are good for a least 5-7 whp.

 

The Cobb app on net maps is good for 24-27psi it is set for 26psi but some people have had it at 27 my self I had a read of 28psi once on beta stage 2 but from what a Cobb tech told me the app reads boost a little differently then most boost guage because it is trying to adjust it's tables from the rom to make it show true boost numbers. A lot of people that used the Greddy infometer said it would only show up to 16 - 19psi max but Greddy said you have to connect it not only to the BUS but also the vac line to get the real boost reading. Cobb does not have a connection to the vac line so it adjusts the reading from the bus. So your real boost could be a little lower or higher then what your reading. The poping you heard could just be back fire from running rich when I was on the app I was running rich too Cobb makes it that way so its safe to use.

 

I probably wouldn't try it again.