Hey guys, I've been looking around for this but can't figure it out anywhere. When I'm starting to move in first it makes that big-rig shifting sound but only for a second I was wondering if there was anything to be concerned over. I am up in Washington state and it is cold as hell, didn't notice this is California though. As far as I know the only thing modified is the exhaust pipes.

Try taking a video of the issue so we get a better idea of what's going on.

I will try after I get it back (someone backed into me) The only other good idea I have is maybe it's cause I'm close to killing the engine when starting

You should not be having any weird noise problems "like a big rig"

Post a vid and we will see what we can diagnose.