I just installed a new tbe - catless on my 02 wrx. Sounds great but my turbo is pulsing in 4th and 5th gear. It also did this before the new exhaust. No check engine light. But in 4th or 5th when i step on it about 3000 rpms and up, the turbo kicks in goes then fades out almost feels like it's stopping (real quick) and then continues to boost, it is in and out of constant boost it feels like. I have looked a lot of places for answers and couldn't find anything. Any ideas would help.