Hello, My ST exhaust pops and stutters a bit on startup, doesn't seem to affect performance at all, and can rev it a bit and seems to clear up quickly. But it is not smooth sounding at all. I have a FP Tune on it and a 3" Thermal R&D. Any ideas on the cause? thought about slapping the stock exhaust on it to see if it goes away, but wanted some opinions before i tackled that process.