This is an emminently searchable topic sir, but here is the SHORT version:
The Quaife is a bullet-proof, torque-biasing, gear-driven diff unit that allows the Viper to accelerate faster without wheelspin, PARTICULARLY while cornering. Straightline accel is perfect-instant 50-50....and you SQUIRT out of corners.
My personal opinion is that BANG FOR BUCK, there is no better (or less costly) mod to accelerate faster-quicker, than a gear ratio swap. You give up 165mph+ speeds....(mere seconds of your driving life)....in favor of HOURS of Seat-Of-Pants quicker acceleration in all gears. Stop-Lite grand prix, interstate pull-away, learn to drive your car AGAIN faster.
Do a gear for 99% of your driving life, not the 1% at the drag strip!
The gear change affects the 20-150 speed positivley, and can affect the 0-20 adversely. If you are a GOOD DRIVER, who can consistenetly get sub 1.9 sec 0-60 times, you can address wheelspin with finesse, feathering, and a lighter flywheel helps a lot. So do lighter wheels and stickier tires...... I have many customers who master the sub-1.9 (with 355s, tires and flyweehl andget 1.6s) and get their best ETs. If you cannot master the spin Mr Bigfoot, youll see your trap MPH rise to 5-7 mph faster, while the ET is only a tenth or 2 faster.
Gears with all rebuild parts in a box, under $600. [08 needs a SERIOUS EXPERT..92-06 does not.]
Gears EXPERTLY instaled in an 08 diff for exchange, add about $1000 more...
Gears and a Quaife EXPERTLY into a diff add about $1800 to the above costs... {Thank You.}