I'm going on a long road trip in a couple weeks and I'd like to put the stock CB exhaust back on to keep the noise level down. I have a reflash for my 3" turbo back that's on the car right now. Is reinstalling the stock exhaust (no cat though) going to screw things up, or will it be ok?

Mods list, incase anyone cares:
- HKS RS intake
- Walbro 255 lph
- 3" TBE
- Greddy profec B
- Reflash

Thanks in advance!

 

It won't really screw anything up in the tune itself, but the overall operation of the car will be affected. You are tuned and boosting as if your exhaust is free-flowing, so with adding that huge bottleneck in the exhaust, your same boost level will cause a lot of backpressure and potentially knock. I would suggest that you turn the boost down to 19-20psi maximum so that if you are bostting, especially in highway gears, you won't be forcing the issue.

 

Thanks for the input. That's what I was guessing. I never run more than 20 psi anyway since I'm stuck in the DSM state of mind where anything over 20 on pump gas got you nowhere. Should I reset the ECU when I do the swap?

 

No need to reset the ECU. Also, no reason to be stuck in any DSM state of mind, because efficient use of a turbo depends on the turbo, not the car. The stock 14b and t-25 couldn't do anything over 20psi, but big 16g's sure could. You can run 21-22psi daily - 20psi is stock boost.

 

Update: The car ran fine on the way there, but on the way back I was forced to buy gas at some no name station. I was worried about the quality of the gas and the temp outside was 100+, so I turned the boost down to 17. Climbing a long hill I got a CEL for random misfire. Then later on when pulling away from a stoplight I noticed audible knock, and the logger was showing a max of only 8 deg timing while accelerating through the RPMs. I guess what I learned is that if I ever put the stock exhaust back on, I need to make sure and get the best gas possible to prevent knock.

 

The best solution is stay out off boost .

 

Tried but, the car was loaded to the brim and had the roof rack with two bikes and a cargo box. needed to 10 psi just to hold 65-70 up these hills.

 

I am curious, but what happens the other way around? Like I'm tuned on stock exhaust but will be putting a full 3" turboback early next week before I get retuned by Al next Saturday. Should I stay off boost the whole week? If I should, its going to be the longest week ever!