How much do you want to spend? A GT350 front upgrade is roughly $1500 all in. I love mine and the car stops NOW, but it is only a front upgrade (at least until Tony figures out the rear setup).
Rotora is a known name and make great products, so you have to determine if the addition (both performance and visual bling) of a rear BBK is worth the extra several grand. Superforged has also been proven, and are cheaper than Rotora, but still over double a GT350 front upgrade.