hi, varly red top battery's are worth a look, they are much smaller than traditional wet battery's so you may be able to keep it under the bonnet and gain enough space to fit your induction kit, this is the type of battery i'll be going for in the near future when i start making space for my bt conversion, but i'm going to mount it as close 2 the strut turret as possible leaving the area in front free for air filter etc. but if u do still want to put it inside, as said above put it in a sealed box and make sure it is very very secure, because if you do use your car on the track or even on the road for that matter you dont want to have the battery chasing you round the inside of the car if you do have a serious ''off''.