Ok, I just added a second amp to my current system.  I am now running the Visonik V408XT 250x2 channel for my subwoofers & a Profile Clarus CL640 75x4 channel for my other speakers.  This is the strongest I have gone in any vehicle so I am not sure if I should get one.  If so, what size should I get?  I have had a Optima Blue Top for about 3-4 years now if that matters.  Any Assistance is greatly appreciated.   

No caps, get a high output alternator if anything.  But they're expensive........

no man you don't need anything for that setup.  I run 800 rms regular in my car and it's fine.  I've hooked up 1000 rms for my subs before for a long drive and it still worked fine.

If you go up to 1000 rms then you'll prolly want to get a 200 amp alternator if you can.  The higher the better.  The other option would to be get a second battery and put in an anti-feedback circuit to boost your power but for what you have you're fine.

Pheonix gold tantrum 300w rms (underrated though it's closer to 400) full range currently running 6 x 9's
RF Power 500w rms D-Class rated at 550w rms by Rockford powering a JL w6 vertion2 and I tell you it PUMPS!!

Cheers