The TRX7 is a very good choice for bottom end riding. The sparks pipe is more like the TRX5, a good all around pipe with plenty of top end. I use the TRX5 and TRX9 for my 400cc puma cylinders as I am dune riding needing top end most of the time. The ESR pipes are readily available at a price you cannot beat. The members here have been using these pipes for the last 10 years. Good product at a competitive price. You do have to realize the plating is not as good as show quality chrome. If you are wanting the best show pipe then you can order it unfinished and get it chromed by your favorite chrome guy.