ok one more question , I hade my system installed my a local shop, I have done alot of this back in the day so dont remember if I can take power from the amp that is installed and shortcut it to the new amp or do I have to run power and neg back to the batterys, I would like to just bridge a 1 foot long line

how big is your power wire, if its 0ga or 2ga you can use a block and split it to both amps if its small it prolly wont be enough to support the extra power

I'll find out the ga , but also was wondering I have a duel battery set up with a switcher and keep hearing about battery chargers like Promariner Marine Battery Isolators, is this something I should add, I have a 99 yamaha exciter with neons and two amps

It is completely dependent on what gauge wire is needed for each amp.

Yes, we need to know what AWG the wire is, and also how long is the power wire? And like stated above you need a distribution block, DO NOT jump directly from the current amp to the new amp.