Flows sound the best to me. What exactly are you having done to the exploder..I mean explorer? TRUE duals? Or just a single to dual? Putting in a "test pipe" or running the cat? I've never heard of "Rainbow Muffler", so I don't know anything about them good or bad. If you go there, let us know either way what your experience was. I would say around $250-300 would be a decent price depending on what mufflers you get and what size pipe you use. But I don't own a shop either. I only used to work in one.....And I wasn't the priceing person. Just the welder.