A month ago, I posted an inquiry about after market exhaust for the WR426F. One kind member responded w/ a review/ rating of several systems and the Thunder Alley Exhaust (TAE) was at the top of his list. On that recommendation, I ordered the Thunder Alley System ). After 3 1/2 week, UPS finally delivered. The installation took only 20 minutes and the mounting hardware mounted/ matched perfectly.It is a masterfully hand crafted pipe and noticeably lighter in weight than the stock pipe. Also reasonably priced, $310.00 w/ SA & shipping. Upon the first firing the deep, round rumble came to life. It was fitted with the straight pipe and was much louder than I anticipated. Made a quick blast around the pasture and down the street trail & back. As predicted, the low/ mid range grunt has noticably stepped up. That's why I bought it. I bought the SA for forest riding and the hope of a little quieter operation. From the house, there are some flood control ditches where I ride to access larger riding areas and don't want to be a nuisance to near by homes. The SA is a bit quieter than the straight pipe but not much. TAE recomends a #168 main jet w/ this pipe which I'll be installing tomorrow. It's too wet to fully test right now but I'll give the full performance report after I've had a chance to WRing it out. I can't recall who posted the recommendation but, Many thanks to Ya !! SEE YA !!