I recently had a STAGE 1 kit installed on a 2002 Twin 88 EFI engine. Runs okay but I noticed a quick pop or crack from the exhaust if accelerating hard to moderate and releasing the throttle to shift gears. Normally occurs at lower gears. The noise is not a loud backfire but a very noticeable pop or muffled crack. Riders next to me have noticed it as well. I took the bike back to the dealership and was told by the service manager that this was normal for bikes with the Stage 1 Kit installed. Is this true or am I getting a line of BS?