OK y'all have convinced me stock 40mm is fine. This is what I have, any suggestions for better performance appreciated. 883-1200 conversion, 10:1 compression. V&H straightshots, SE intake with ignition, the one that retards timing at WOT. Carb has been jetted w/ yost tube. What about a thunderjet or something else. Names of suppliers if a part is suggested would be great too.

 

Carb sounds just fine...have your heads re-worked and/or go with a set of cams. You'll get some pretty good gains off those. You can also swap to heavier duty valve train components to up your rev limit a bit and really get the most out of each shift.

If you REALLY want to go all out check out Zippers'...they have everything assembled in kits and can really fill in some blanks for you if you give em a call and let them know what you're after. There are lots of options to make SERIOUS power, it all just depends on how much $$$ you're willing to drop

 

here's another choice.

http://cv-performance.com/index.php?...od&productId=2

 

You need to contact Head Quarters and get there carb kit. That Yost thing is a piece of crap I have (stupidly) tried one twice and they don't work. You should also talk to them about there ignition system they have custom tailered ignitions for Sportsters. I've tried those SE ignitions a couple of times (stupidly) and found they don't work either.
Head work, Head work, Head work is what you need and some cams more suited to those over size Thunderstorm heads.