Cameron, I have had similar problems with my Dellorto's, mine are 40mm DHLA's off of an Alfa Romeo and I got them off the internet for a really good price. On mine I have an Air/Fuel ratio guage to help me tune, and it seems whenever I rev it up, it pulls awesome then just dies off at the higher rpms (6000 rpm to redline). At the same time the Air/fuel ratio guage goes big time lean. I have tried to get rid of it by changing to an electric fuel pump and regulator and adjusting fuel pressure did nothing. I rebuilt the carbs and cleaned them out really good, with no luck...so I think it's just a matter of getting the right jets (slightly richer) which are hard to get for Dellorto's (at least it is in the US). I also think I could go with larger chokes on mine as well, but that won't help the already lean situation. At one point I had the car running super rich and that high rpm problem went away, however it ran like crap everywhere else. If I were staying with the A series I'd investigate it more, or go to EFI, but SR20 is the only thing on my mind anymore. Good luck!

-Andy