There are some notes here from track guys and the question of whether the cars that do alot of road courses should go to 3.55s. For years I would have said leave the 3.07s alone if you primarily do road course use, but that , I feel , changed with the Gen IVs. With a PCM and 3.55 gears the cars pulls farther through the gears than you would expect, and has tons of grunt out of tight corners.
Ted Hughes, who is also racing in the ACR-X cup, was more than gracious in letting me drive his 08 Viper Violet ACR for what ended up being an entire morning session ( I did say he was gracious, I said nothing about me not being a complete unabashed track ***** ). This absolutely blew me away from previously running alot of Gen IIs , as the extra rpm allowable seemed to be matched perfectly to the 3.55s. We also had installed headers on this car and it ruined me for life ( three weeks later there was an ACR in my garage ).
I will be the first to admit that I am completely wrong about the gears for the Gen IVs, especially, as I still suggest folks stay with 3.07s in the old cars to keep shifting at a minimum. The extra rpms and the power up top on the VVT 8.4 means the gears work and the power band is sweet -- not alot of shifting necessary. I would not recommend the 3.73s for road course use, but for the street and the strip , that may be the way to go --- big rush riding in Mark's wicked wagon.
Lastly , for those folks that run really fast tracks like Willow Springs or Road America , the 3.33 might be better , or possibly even stock, but I have a feeling the 3.55 is the best overall gear change , as it is great for most of the newer tracks that limit speeds to maybe 130-145 tops , even in a Viper.
Gotta get gears for my ride ............actually gotta get alot of things , damn addictive machines!