figured you guys in the n/a area could answer better than the drag one.
I currently trap 105 mph on 22's, pretty close to my 8200 rpm (stock head) rev limit, still in 4th gear.
Is it possible to still stay in 4th with such a low red line of 8 grand?? I don't mind upsizing tires to 23/23.5. I am just wondering that w/o more revs will a 5.1 f/d be beneficial to me as I'd be seeing 5th. ---Or is it worth it, shift fifth. and trap 11X?

or is the 4.6 the way to go for me?? (i like to start w/ overkill)

and lastly. and i don't need the flames for it but. its a pahntom grip diff(since 97), any probs there w/ f/d's and them?

 

I would go with the 4.6. Using the 5.1 even with larger tires you will hit 5th. Doesn't matter how much power you have, having to go into 5 will kill your ET. I played around with going into 5th versus letting it wind out and winding out netted me faster times, even though I was way out of the powerband. (D16 w/close gear set BTW).