I've got 2 cubby spaces behind my seats in my MX5. I can only fit either a 6.5" or an 8" W3 in them.

Does anyone have any experience with them?...

and...

Would you recommend I go with 1 8" sub, or 2 6.5" subs.

 

I have a 10" W3 and I love it but I can't comment on those sizes.

My first thought is that 8" would be better for the bottom end.

 

^^ Yea, Im thinking maybe 2 8" woofers.

 

Yeah...if 8's fit...go for 8's.

6.5's has a different bass level and sound...IMO

But 8 is still conservative.

Should sound good and pack a punch.

 

8s are good for midbass and should be installed in pairs (midbass is usually stereo).