ecu should be fine, depending on what you are running. unless its like 10 subs or so...2 1.5 f caps will hold it easy, just get a good battery like a oddesy or optima. skyline bateries are known to be shit, as is mine, and having a reliable battery would be a god send(i have no $$$)
i had an excel with two subs running off an oddesy and it never went flat or showed any signs of weakness(lights dimming)