Go to Unitrax or Taylor race, for sure.

They built the rear end in our world record Ballista among many others and we have never had a problem.

We also use them in our ACR-X's after the factory rears died.
Nothing compares to a full quaife.

Drag racing, road racing, street driving, the quaife is the answer.

As for the 3.55 gears, it comes down to where your using the car and your money.
More gear in the rear is for lower torque levels and more shifting.

Gear multiplication makes more power get to the wheels, but shifts come sooner and more often.
3.55 gears means less traction in all the low gears.

They higher the torque, the less gear needed and the bigger gap between shifts, but more importantly traction.

If you make big power, don't waste your time on gears, it will slow you down shifting and you will run the motor harder on the highway.

If your upgrading the rear end, most builders wont reuse your stock gears, so your most likely buying gears anyway.

Spend the extra money on a quaife, you wont regret it.

To put in simple terms, on a road coarse, you can shift in the corner with the quaife and most cases not lose traction.
Try that on your stock end, but let someone know beforehand, so they can film it for youtube.

A quaife gets in and out of corners faster.

Gen 4/5 cars have a simple version of a quaife, which is one of the main reasons they run so fast on the road coarse.

If your racing is limited to less than 140mph, you will see nothing from 5th and 6th gear anyway, even with 3.55 gears.
If you cruise more than anything, you will just be adding miles to your motor, and have to get the speedometer re-calibrated.