I have a Hot Rod Shop, been in business for better then 30 years. The mandrel bent exhaust tubing that Performance-Curves sells is far superior to anything else I have used. I custom fabricate headers and exhaust systems and this tubing is great to work with! All sizing on the tubes is excellent, inside and outside diameter along with wall thickness is right on the money! The quality of the tubing is great and requires minimal clean-up and prep time prior to painting or ceramic coating!!!! Excellent product and excellent service, I highly recomend Performance-Curve and will definitely be a repeat customer. Dave Severson Dave's Hot Rod Shop Madison, SD.