AU engines pre-modified

[EB Pete]

Originally Posted by Perana XR8

Better flow (unless you have an EF/L XR head) with smaller ports = better air velocity, smaller valve stems, supposedly has better coolant passages too for more even cooling.

The mains have standard Bolts going straight in but then also have bolts going in at 90deg to the other bolts.

that does sound alright! 4 bolt mains. so you could get alot better flow out of the AU head by porting/polishing ect then say an ED head?