Used s2k head bolts will provide much better clamping force than new ARP studs. But as stated they require precision measurement to be deemed reusable.

AP1 retainers will be fine, but require a very trained eye to spot early failure. So AP2 retainer and cotters are a good idea for that reason.

AP1 and AP2 (04-05) engine harness are plug and play/same.

 

what is the oem parts number of oem retainers ? i need how many to make the change in my ap1 heads ?

 

Is the AP1 Cylinder head casting same as the AP2 07? The know that the valve train is different but dont know about the casting.

 

The head casting changed in 2006.

There is no air pump porting in the 06-09 head.

 

If I was to use an aftermarket ECU & harness & change the inlet manifold, could I use an F20C AP2 08 engine in an AP1? I know the AP2 uses a different crank trigger wheel & cam trigger wheels, but could a aftermarket ECU manage this?

 

I think the AEM Infinity would work, probably others as well but don't take it for granted.