can someone tell me how do i extend my + battery cable so i can get it to fit the Optima Battery?

 

you got the wrong optima. you need the one with the connectors at top,top not top,bottom.

 

its a red that has a r for reverse.

 

www.remybattery.com

they have the correct group size.. .and no, you don't need a R type... the correct group size comes with the correct terminal placement.

 

If you get the right one it's a direct drop in. I have info, pics and PN's here:

http://www.scoobymods.com/forums/showthread.php?t=4405

 

You apparently got the "universal" 35/75 with both side and post terminals which is what is usually sold in the stores. While it's physically the same battery in terms of size and capacity as the standard Group 35, the post terminals are in a different location so the starter cable is a few inches too short.
If you possibly can, return it and get the right battery for a drop-in replacement (you will probably have to order it online). If you're stuck with it, it isn't that big a deal to install it, I have this battery because it was the only one available when I got it 3 years ago. Go to a parts store and get a "universal starter to switch" cable at least 30" long, it will be 4 ga. wire with large ring terminals on both ends. It will cost about $5. Disconnect the existing cable from the starter and battery clamp, and install the new cable in its place. You can leave the old one where it is or remove it, if you leave it the new one can be tied to it so it follows the same path. This is important for proper strain relief and protection from engine heat and movement.
Of course disconnect the battery before installing the new cable.

 

The place I got mine on line was less than 100 shipped if I remember right. Link in my post.

 

My friend had the same problem installing it into the STi. You have to loosen something that gets in the cables way if I remember correctly. It's further in the engine bay. It was a pain in the but...and it took a WHOLE lot of yanking(battery and cable) in order to get it to fit. It wasn't short by much either, btw.