Suggestion,put the battery in the passenger footwell behind a footrest that the passenger will thank you for as it gives something to brace yourself on if driven hard.

Footwell is a good idea. While on the subject of batterys ,in the back of the battery book in the wholesalers is a list of all the different sizes of battery with the cca listed. I noticed that the 100 series in the yuasa measures 11"x7"x8" which has 650 cca. Thats the same output as a f@@k off great truck battery, so if space is tight its worth going to the book to see what else is about size wise.

Bob

I am not keen on something that is full of acid and fairly heavy sitting on f/glass albeit strong and well made at that height.

I have a little 5Kg Odyssey Battery PC545 for my car. No problems. Didn't use the car for 6 weeks and got home. Started first time (2ltr RS2000 Engine). Kit cars don't need big batteries. Its a gel battery so you can mount it any way you want and it can't leak even if you split the thing. I got mine for £55 quid off Ebay.

Now that I think of it, my Civic's 45Ah battery (fresh) had trouble spinning Sierra's 2l Pinto engine at about 0°C. Maybe I just lucked out with a lower current CVH starter?