Spent some time agonizing over where to mechanically limit VTC advance (variable exhaust cam timing). Supposedly a full 50 degrees of advance is safe, but barely, on the 06-08 K24A2 (which came from the factory with only 25 degrees of adjustment). The 04-05 K24A2 motor actually has slightly less aggressive cams, but the pistons' relief for the valves is smaller and it's possible under some circumstances, such as catastrophic oil pressure failure, or mis-shifting and over-revving the motor, where a full 50 degrees of potential advance might cause the valves and pistons to collide. 45 degrees is supposed to be safe, but I couldn't find any hard data, so I opted to limit it to 40 degrees.
Supposedly allowing another ~15-20 degrees of cam advance is good for 20 ft-lbs of torque across the rev range.
