so after putting a Mamba Monster on my truck with the RC-Lights 911 police light kit. when i turn the truck the lights built in to the truck dim (not the RC-Lights i installed) everything is stock other then the ESC and Motor. i also have a capacitor plugged in to my RX local hobby store say i needed it being i was running all the light but don't seem to do much of anything. I was wondering if i would have to get an external BEC or something to fix this lil issue

this is the capacitor i have on the truck