Gen III tranny options?

Cost is what is gonna suck. If you're not doing serious drag racing, a 545rfe would probably be the lowest cost of more than 4 speeds. Nag 1 is a lot tougher, but, twice or more the cost of the 545 to get wired up. Considering a manual as well?

Plan is to attend the Swedish version of Street Week, so drag racing -YES SIR! Hoping to get into high 6's. I don't know if you can call it serious drag racing though.
What's the big difference from the A518 46RH I already have?