GermanLook Forums - Flat spot/ preignition???

hi guys, its been a while... so here is my first post for 2008!!

ive changed my exhaust system from a crappy modified kadron manifold with even crappier j tubes and a straight through muffler to an empi manifold and a single quiet pack muffler along with stock heater boxes. I know that the heater boxes present a restriction in airflow, but im not willing to go through 6th winter without a heater...

also changed my throttle linkage on my 40mm duak webers from a type 3 one to a hexbar.
the engine runs a 009 dizzy with 10 deg static advance and the problems are

cold exhaust gases with an otherwise extremely hot exhaust system (heater works magic!!!!) when the engine oil is at 80-90 deg running rich on 95 octane unleaded.
and a hesitation in acceleration around 60-80 kph (50-60 mph) in 3rd gear if you accelerate smoothly. if you give it the beans from the start there is not prob at all. any guess???

carbs are synchronised flowing 2.5 at idle and using 55 idle, 125 main on f67 emulsion tubes with 190 air correction. i will bet that i got 36mm venturis...

revving in neutral is criminally fast just blipping the throttle pedal gives like 3k rpm instantly and im considering some kind of rpm limiter.

otherwise engine is AS41 with stock 1.6 crank and rods, 90.5 cylinders, 044 heads (40 intake 35.5 exhaust) and electric fuel pump @ 3bar constant

im considering droping to 50 idle jets and 120 main while keeping the f67 emulsion and 190 air jet and maybe giving another 2-3 deg advance

any suggestions?? need help

Thanx in advance
Chris