it generally improves boost response and torque. you'll see more 'gains' down low, then you will up high.
I'd recommend going to 15, as 13 will foul plugs more readily then 15 degreee. but i'd also be careful/safe with boost and fuel by backing up any timing changes with 3 pulls on a dyno.
"As the Z32 gets older and decreases in value it becomes affordable by lower income and often less desirable people whose tastes reflect their personality and social standing.- Marshall 17:37:05 10/10/03
