Vortech S/Charger guys--advice please!

[5.0-man]

I recently built a 89 coupe with a N/A 306. Combo is the following:
Pro-M 77mm
70mm T.Body
Edelbrock RPM manifold
Trick Flows heads
Eagle rods
stock crank
long tube hedders etc... Well the question is about my pistons. I have 10:1 trick flow pistons. My car ran a best so far of 12.33 @110mph. It recently slowed down to 12.50s. Havent found the problem yet. But I would like the car to run 11.50s. What supercharger would I need to run these numbers and would I need to lower my compression? I know I COULD run the A-trim for sure with these pistons, but I don't know if it would be enough to run 11.50. Any help by experience would be appreciated. Scott

------------------
1989 LX Coupe, N/A 306. Pro-M 77mm,70mm T.body,Edelbrock RPM intake,TrickFlow heads,Crane cam,Eagle rods,10.1 pistons,Hooker long tubes,MSD 6-AL,C-4 W/3800 stall,4.11 gears,SSM's 12.33 @ 110 mph. Car is still being dialed in. Pictures and info on my webpage. (LA Mustangs) http://www.louisianamustangs.com