I have the SPR 127550 , 3:73s Kenne Bell 2.6L 14psi with a stick and would not hesitate doing them again. I was worried also before I got them, But now Im very happy with them. No driveablity issues at all even with a DFX clutch and Drag radials in the rain.
I'm an old man too.
Dyno with 15 degrees timing