6sp manual with recaros, now with Hennessey intake, AR Headers, tune (about 615 HP -- 521 to the rear wheels per dyno). Car is a blast, but traction is an issue, even in 104 degree weather. Just have to get over the fact that you can't floor it in 1st or 2nd in any weather without blowing the tires completely. 3rd gear hooks up in 90+ degree weather, and we'll see about cooler days this fall! Interior is very nice, but there is a bit more interior noise than in an audi I owned. 14-15 MPG average really isn't that bad for a 600HP sedan. Gadgets are very nice. The 8 inch nav touch screen is impressive. Excellent toy if scaring three passengers on the way to lunch is your cup of tea!
The manual transmission is pretty much perfect.
Larger tread in the back (325s would likely hook up better). Lose the highly restrictive intake and exhaust (that's what I did to gain 57HP to the ground)!