I adapted a 130 amp alt on my boat to replace the oem 53 or 63 amp it had for similar reasons,voltage wouldn't hold at wot running all the extra stuff,a big fuel pump at 75 plus psi will draw 20 plus amps if not 30 (I have blown a 25 amp fuse),plus aftermarket ignition,plus your injectors and all the other stuff. You might want to try running some bigger wires too from your batteries/alt to the engine and computer harness,I ran a small battery cable from my alternator to the connection running to the battery to ensure I got full advantage of all the extra power,Smitty

Hi Smitty,
Can you give some more detail as to what was needed to make that adaptation for the alternator. Do you have any pics, etc,.
Bob

I found a alternator in a catalog rated for marine use,it was very close to fitting except it used a v-belt instead of a serpentine. I used a small spacer(about .050 or .100 thick) and the dia of the shaft to get my pulley to line up opn it and not rub the alt body,it bolted to my stock bracket (it had 3 holes and one of them lined up,I attached the only pic I could find),couldn't tell you much more except its definately fatter in diameter (the old one was a hitachi style),it was 5 or 6 years ago,Smitty

Thanks, I will look in to that option.
Bob