Optima Yellow tops are the ones you want to use for car stereo. I have also used a red top before as a second battery in a large system with good results.

 

was using the blue tops actually...marine ones, but still the same amps as a yellow top if i remember correctly. Blue went with the theem in my trunk and under the hood.

 

James.....I got a 180+ amp alt from Wrangler and their list is $490, but you can work a deal with them. The alt actually dyno'd at 200 amp's!Call Steve Schoder and tell him Glenn sent you.
I put it in myself with 1/0 gauge wire to feed my batteries and system. Not that hard to do!
Oh and by the way, for the 350Z I'm trying 2 Kinetiks HC1800 batteries this time as they are the same power as the Hawker Odyssey 1800 batteries but a smaller size and weight. I have seen nothing but rave reviews on mutiple car audio sites!
http://www.kinetikpower.com/powercells.asp

 

Zspl,
The 140amp alt was the best they could do with a 300ZX alt, as factory was 90amp for the TT's. If you noticed I said I had the 2 Hawker batteries and Ohio gen alt in my 300ZX.
I did just get my 180 +amp alt from Steve at Wrangler a couple of weeks ago, so I blazed a trail for you there bro! Better housing to work with. It actually dyno'd at 200 amps with a fast low RPM ramp. Good stuff!