fm transmitter

wanted to know if anyone is familiar with modifying an fm transmitter for a stronger output signal strength. i have bought 3 so far and they all suck out of the box. i found how to modify the belkin unit, and it worked great. i recently bought a monster carplay unit because it charges the ipod, but the signal strength needs to be stronger. my xm as well as my modded belkin unit dominates it on any station. is anyone familliar with the mod procedures for the monster carplay?

fm transmitters suck dude, try getting an fm modulator....they are a lot better, trust me