what is a good aftermarket clutch? king cobra?

If you are making within 100hp of the stock ratings then the king cobra an excellent choice!!! I absolutely love mine, wouldn't trade it for anything. If you are blown or spraying then I would step it up to a spec stage II just to be safe. King cobras are only available on new edges with t-45's, I think they fit older models with the t-5. What year, trim is your mustang? You are going to want to get your flywheel resurfaced when you change the clutch, should only cost $40. Where I got my kit>>
http://www.americanmuscle.com/kingcobra.html
Centennialstang to be honest I have heard nothing but bad things about ram products.
 
Another option is the FRPP 11" upgrade cobra clutch (upgrade for 99/01 cobras). You need a 99-00 GT for the kit, which includes clutch, TOB, PP, and new flywheel (8 bolt) for under $200.
 
Samz281, how is the pedal effort on your car compaired to stock ? I am thinking about a CF dual friction for my dad's Bullitt and possibly for my drive if I end up converting to a manual trans.

I have also heard of a many people have bad experiences with Ram clutches and have had my fair share for BS problems dealing with Spec (who I now HATE). The king cobra clutch is an excelent clutch IF it will fit your setup. Let us know what year car you have/what trans.
 
What year car?. King cobra does not work with the 3650 tranny (mid 01-04). I have Mcleod and love it. Pedal is not that much more than stock.
 
I have a Centerforce Dual Friction and aluminum flywheel and I love it. I have a 99GT with a Vortech and 371rwhp. I have probably 16 runs at the strip with this combo and with BFG Drag Radials have run 12.249 @113. Break-in was not bad I had approx. 550 miles on the new clutch before I made my first pass.