I love my S3 engines.. I now own 3 an a S5. I had so much trouble out of my v-spec I traded it outright to a buddy for his used S3 straight up and I think I got the better end of the deal. It is so smooth an easy to tune an drive. Not like the v-spec.. that thing was ballastic and I run mostly shorter tracks with technical layouts.
I use 30% byrons gen 2 fuel
Not sure which plugs I am using or inserts
I do know I need to work on that as my fuel mileage is lacking a bit running a 2050 pipe