When i had my ST170 i had a magnex exhaust with de-cat, panel filter and superchip and it drove well. The button doesnt fully turn the traction control off IIRC anyway. Only way to do that is remove the fuse but that also turns the ABS off When i had it on the rolling road it didnt get full power anytime the fuse was in also. Wondered what the feck was wrong the first time i tried to rr it and it was 135BHP. Took the fuse out and it was fine.