If you have removed the short reducer tube in a stock 450/510 muffler it performs the same as a straight thru Arrow mufler because what you have is a straight thru Arrow muffler. I have a modified stock muffler and a full titanium TC exhaust made by Arrow and have run a modified stock muffler on the oem smr header. The TC header is quite a bit different but the mufflers are basically the same internally once you remove the tube although the materials are different. Don't waist your money. The 610 exhaust is another animal, those you need to toss.