This is for all you guys out there who give me shit for the price of my pipes vs. just buying some shitty $1000 CCI chrome ones. This is an all stainless 2 into 1 exhaust for my knuckle project. Stainless is always a better choice than chromed mild steel for many reasons. Reason 1: chrome will peel off eventually, no matter what you do.
Reason 2: exhaust gas is corrosive, and it eats mild steel for breakfast. You don't realize its happening because you have chrome on top, but inside your pipes you have solid rust.
Reason 3: (almost) all companies that sell chromed pipes, no matter how patriotic/expensive they seem, have their pipes made over seas. There are literally no enviornment protection laws over there so they can pour their excess chrome sludge into the dirt, saving you a few dollars.
Reason 4: if your chrome gets scuffed up, your fucked. If stainless gets scuffed up, you just buff it again.
Here is what I do. My headers are 321 stainless, and the collector and muffler are 304. I made the muffler core by plasma cutting V shapes into a stainless tube, then bending them inward to create baffles. I have done this on a few bikes before and it makes a great sound. I also do a male/female slip fit at the merge end of the core tube inside the muffler. This is due to the fact that the perforated inner tube gets hotter than the outer body of the muffler. When this happens the inner tube grows more than the outer, and will break itself apart over time if you do not give it somewhere to expand into. Think of that every time you turn your bike off and hear that "tink, tink, tink" sound coming from your pipes! I also always machine the first few inches off my head pipes from stainless billet stock. This is because (esspecially on evo's and twinkies) the welds that hold the mounting flange/ mushroom onto the end of the tube get so punished by the high temps and vibration that they eventually fail. If you are riding when they fail you may not notice at first, but your exhaust valve will get hit by cold air and crack- meaning you will need to take your whole top end apart to replace it. I machine the flange/mushroom piece out of a solid chunk, then make a ID press fit into the tubing, then seem/plug weld it together. The tubing I use is twice the thickness of typical mild steel tubing. Because this engine is only 61", I made the head pipes out of 1 5/8" tube for the first few inches, then up to 1 3/4", then the merge collector to a 2 1/4" outlet, then a cone/reverse cone muffler. All I have left to do is mounting tabs and final buffing. check it out-