Which battery do you use/recomend?

and whats the differences in like34, 51 etc what do the numbers mean?

 

bump bump bump

 

I'm using a yellow-top group 34. It rocks. I live in an oven, so the OEM battery went south almost immediately. The Optima gave ma a ton of additional cranking sped which gets the motor started really quick.
Plus, I can run all of my A/V stuff at shows for hours instead of minutes.

The "group" designation refers to the fitment - where the terminals are located, their orientation and the physical size of the battery.
Optima doesn't have a battery that they spec for the RX-8, so if you use the group 34, you will have to extend the positive terminal with an inch or so of aluminum bar stock to reach the (+) terminal.
The negative will fit just fine.
This is because the group 34 is physically backwards compare to the OEM battery.

 

if i got a yt 34r it would be the same except reverse do i wouldnt have to extend the pos terminal?

 

more recommendations??

 

After a good bit of research and calling practically all of the Delaware parts shops I found the D51 yellowtop optima fits our cars perfectly. The batteries come with a little tray attached to to top of the batt, it clips underneath the battery and puts it at the perfect height- no extending cables, the battery clamp goes back on, no wiggling around in the batt box, basically a perfect fit and match. my 8 flooded and I ran down the stock battery in about 2 minutes- went out picked up the D51 dropped it in and IMMEDIATELY the car started up from the quicker rollover of the starter. I plan on adding more AV and this was worth the money.