Yeah, 6 speed FTW no questions asked. Havent had a single problem with mine yet. 700+ hp 149+ traps, 1.61 60ft's, several blasts to the end of 5th gear.
If you want to make your b13 trans last as long as it can, Valvoline 85w140 either conventional or durablend. You will notice a huge difference in how it feels, shifts smoother, and just overall protects the gears night and day.
The 6 speed is nice especially if you drive the car alot on the street or use it for daily driving. Cant beat it.