Depends on your definition of trails, fast trails will be fine with CPI's. My mods are in my sig and I even hit some slower trails once in a while. I also think that for a stock stroke/cylinder setup, the stock carbs will do just fine...they are very under-rated. You'll likely see more gain switching the pipes than the carbs, either one will gain more top end and loose some in the bottom. If you do go the 4mil route then you will deffinately want to look into some larger carbs. Who did your portwork?? There is likely a substantial amount of power to be had from some more aggressive porting as well(aslo a gain in top loss in bottom power). As far as your compression is concerned, that is a very good number for a play/drag engine. Any more compression will hurt your over-rev. As far as the reeds are concerned, for a stock stroke/cylinder setup I usually recommend ported stock cages and aftermarket petals...The VF's won't net you much gain for the cost. As far as the mods supporting a 4mil, they are pretty much the same mods needed to support a stock stroke of the same style porting. Just my .02
-slo