Don't put a CRF cdi box on your trx. Get an aftermarket trx box...Never mix bike parts unless its made for the trx...Or you have an CRF450 quad like me, then its all good. And yes the HRC kit has the same cam as the CRF, the same uplift. Never put any parts you are not sure about into your trx off of a crf, the two engines seem the same BUT ARE TOTALLY DIFF. The crf revs much higher than the trx, the crf box will just make your rebuild times go from every 50 hrs for normal riders, to about 20-25 real quick if you don't watch it. All cdi boxes do is make the engine limit higher for rev. If you want a better spark and timing which I also watch doing unless you want to see your cam laying in the bottom of your engine, is add an Ignition(MSD are the best). Just don't mess with it, put a lower tooth , or higher depending on how much more pull for lower, and higher top end for higher tooth. Note this front drive change will effect your quad extremely in some cases you have to rejet even with a front sprocket change. That is the best change you can make, other than that, have your head polished, new oversized vavle/job, intake and exhaust. You should be lucky too, we don't have to buy 2 cams like everyone else. Other than that ride on!