Research seems to indicate the Honda genuine pipes are exceptionally good! The best power from an NSR Stephen has seen on the dyno was 66 on genuine pipes.
However, they weigh a LOT more than aftermarket stuff.
There's not much difference between all the aftermarket pipes to be honest, most people seem to get just over 60hp no matter what they have. Some pipes allow a little more over-rev, some have a slightly wider power band, but overall there's not much in it.
When I was racing, I had 63hp out of mine with no air filter and Tyga pipes. They top out at about 11,800rpm (fine by me - I like my crank!) and survived a couple of crashes bashed but intact.
I'd recommend Tyga as I've uysed them, can't say for the others...
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