This is driving me up the wall and almost ready to go to a speed shop for help. Have a 355 SBC, Turbo 350, Electrict fuel pumo with regulater set to 5.5 pounds of pressure. HEI ig, Edelbrock Thunder 650 ( all in a 23 T-Tbucket with outside headers). Under WOT, from a stop, terrible bog and sometimes backfire(flames) through carb. Sometimes also does a temp bog at speed when going WOT downshift. My timing is set to 12-40 with vac advance hooked to full time vac port on carb. Idles fine and if just push down on excelerator, runs great. Only when slam to floor does it bog and really bad. No black smoke, seems lean condition. Any advice folks?