Hi Munro
I have fitted the Pioneer sub in my Type R and it sounds quite good. You will have trouble mounting it where you have suggested as the seat will no longer fold down. The amp will catch on the step on the floor, but this can be remedied by mounting it further forward on the seat
I mounted mine underneath the single seat just like Swindon Japster and took a power feed directly from the battery. This is not to hard as long as you follow the instructions and pictures that were posted by SJ. If you want some pictures let me know and I'll get some for you before the weekend
