Whats the maximum advance you can run before you start doing damage to an engine? I took my car for a ride last night and noticed it was pulling harder then normal on top end. Checked the timing and it was 50* advanced. Backed it down to 38* total and it seemed to not pull like it was before I moved it. Its a brand new MSD 6al box with billet distributor. I have the 20* bushing in it and run 18 initial and all in by 2500. I've heard some people say never go over 40. Is this true?