Hi guys, have a question 4 all the tech heads on here! i own an EG9 and when i bought the car i got a spare head with it, the head has a stamp on it, PR3-1. my VTi has a stamp on it, PR3-2. my mate has a standard EK4 with a PR3-2 head and he has another EK4 that apparently had a type-r head fitted and it is stamped PR3-1. are the heads any different? can some one shed some light on this? would it be worth my while swapping the heads over? any info would be greatly appreciated!!