Muffler Install

[Shawn T]

Wow, it has been a long time since I have been on this site. At a new job and it's finally not fire walled. On my 60 duramax LBZ I installed a poor man's turbo back exhaust. I just cut the cat off and replaced the stock pipe and muffler back. I went from the stock diameter pipe (3 inch, i think) into the dynamax 12" muffler and out 4" with a 5" tip. When accelerating hard and at high RPM's it sounds like it's gasping or whistling from the intake. My filter is clean and it's done it ever since installation. Is it because I didn't go with 4" all of the way from the turbo back? Also, when pulling a trailer on high altitude climbs and hilly terrain, I get an SES light for about 2 days and then it resets on it' own. I'm assuming this is a low back pressure issue. Does anyone else who has modified thier exhaust get this?

Thanks in advance

 

P.S. It's definately not turbo wistle. More of a woosh, with engine revving, turbo whistle is drowned out. Also, I didn't even notice a performance improvement.