how much different are after market pipes then stock pipes, why do the put out a little more hp?

They are more precisely made, and usually tuned to run at a higher rpm, combine them with a nice port job, some clutching, reeds, and look out!

,, on a ZRT600, the aftermarket pipes spin at around 9000-9200 rpms- more wear and tear, but definately faster.

when i looked into putting pipes on my 96zrt i wanted the dyno sheet on them from psi and rpc,both companies bocked and when i finally did get some info i find that both sets of pipes actually made less horsepower thruout the whole power band until they starting to rev past 8400,and they made peak power at around 92-9400,i ended up putting a set of 38mm tmx flatslides for better bottom end than stock and awesome top end,i never did have a problem running any piped ones down and ran only to 8600rpm

Your right on 900 geek, my experence also. zrt 600 stock triple pipes work awsome way more torque espically the older 95-96. But with the newer style 97-98 blend/grind that inside flange right at the entrance of the pipe.

A few of us had zrt6's with different stuff and our buddy's with D&D stuff always seemed to work the best. just my .02 though
and you HAVE to reclutch.

What is the grinding technique for the flanges on the 97...all the way around and all the way back??

look inside your pipes right at the entrance you will see the factory extrusion flange, just blend it into the pipe.

Cool....Thanks. :div20: