Tony,

Thanks for posting the results.

I've never seen much diference between the M1 and the SD, I just prefer the SD because it'll fit under the hood of a b/e even with a small spacer and the SD has runners that are easier to work (The M1's are kinda tall and narrow for the same sqare area.) A lot of the flow improvement to the SD is in the 'as cast' roof so It needs a little spacer to "fix" the turn radius. The rest of the changes are really just opening up the runners for more flow area which a stroker likes.

Your results are skewed by a the too big headers, a torque curve is also a MOMENTUM curve which has a big effect on how a motor pulls through a load. Your motor for its compression and port area was at a big disadvantage below 4000 because your motor had no "sweet spot" to gain RPM bacuase the exhaust had no velocity (lazy). that effects overlap scavenging and when you have smallish runners to begin with....well, it all ties together.

When you put the 2" on it it'll feel a lot stronger from about 3600 up and it will broaden the torque curve AND make more power. If you keep the SD I can shoot you some porting ideas but I think I'ds go with the indy dual plane with some pretty easy to do lower plenum work, that will be a better all around intake for the street and won't cost you any appreciable power up top. If it did, I wouldn't run one in max wedge form.