Hey guys. Tomorrow I'm finally installing a 9 inch stack I made and making it 4 inch all the way through after the down pipe on my '95 12 valve 3500. Since I'm doing the exhaust I thought I might as well make a 4 inch down pipe for it. But I heard from a few guys that a bigger down pipe would make it run worse. It didn't make any sense to me because I always see 4-5 inch down pipes on trucks making some crazy power. My truck is no where near any high hp marks but I thought it would be worth while since I'll be down there. I appreciate any thoughts on a 4 inch down pipe on basically a stock 12 valve.

 

That is so stupid and who ever told you that has no idea what there talking about. 4'' DP is fine. Better for flow.

 

Not sure who told you that... A bigger DP is a great addition to any truck