Emaxx questions

I will be getting the FLM hybrid bulks with 1/8 diffs in the near future when i upgrade to lipo. Mike was right about the diffs i had, they were too big. Is there a feigao 7xl without a built in heatsink, the only xl i could find on the website without a heat sink was the 8xl. I guess i will be keeping the original spur, what size pinions should i start out with? Pretty sure 15 is stock, how high could i go without damaging the 8xl? Don't want to do more than 40 or so right off the bat.