I removed the muffler and replaced it with pipe..after 10 mins of driving it stalls, it cranks/turns over but then shuts off..Could it be because it's losing too much back pressure? I might just put the stock muffler back on. I have a 07 RRS S/C. I removed the Fuel Pump relay switch and put the same one back on..and it starts up and runs normal for about 5 mins then does the same thing all over again...Any help would be highly appreciated.