Coz you're good at this stuff, I'm asking your opinion!!!

Would you say that theres much point to fitting an 8" sub into the cabin of a car?

Would I get virtually the same out of a decent set of 6 1/2s?
I'd have more room for a start.....

Bit vague I know but I want your opinion before I tell you what I want to do!

Ive done it.... using JL 8W6's which have a very vary small enclosure size. I built a fibreglass and MDF enclosure to fit in the rear passenger footwell.I was amazed how easy it was to still sit in the back. Also it looked realy stealth. Walk by and look in and it was very hard to notice. I loved the sound been so close.Ive got 2 units. but now wanting to fit them into a MX5 . Now that will rock!!