what is your price range?
here are some of the popular ones
the pipes on this page are good
http://www.cc-racingengines.com/inde...4ac1cb23ff2ec5
heres another good one (the steel one)
http://www.americanrcboats.com/produ...gineacczen.htm
and another
http://www.redlinemotors.us/#/pipesa...tpa/4521241598
and there are heaps more