I've had a piper 285t on my S1 it went knackered due to age so i was advised to go for 285t2. I,ve got ajustable boost but when i drive at 10-11 psi it's fine with the 285t2 cam then i turn it up and it's better it doesn't seem to affect my normal drivin but it does seem to be higher up the rev range when it kicks in about 4000 rpm but if ya just gona be sticking with the 150 mark i'd definaltly go for the 285t