Im trying some Mikuni taper bore 38-44 tmx carbs this year. Have some lean conditions in 1/4 to 1/2 throttle but working them out. I also run the jaws pipes but had Richard from B.C. build them for me, he did a great job and they work excellent. I had Lowell Horning port my engine and am very happy with his work too. I have an Ekholm tunnel and suspenion too. What is your cranking compression at your lowest altitude? Im running about 165psi at 2200ft. Just running premium fuel with no problems at altitude. Pretty happy overall with the whole unit.