my 16th was before 2001 so it was full 17th for me......am qualified spark did 2360 for 3 years.....16th....17th.....never did 2391 though - although test & inspect comes pretty easy when doing it regular...was going to do it but dont want to do 2391 if it will be re vamped to comply with 17th, will hang on a bit for that........been sparkying for 11 years now