hi av8to1977 - i'm turning a wide 18/6 and it has a dual output tube diverter exhaust. I have also put a C&H ignition and timed it at 28 degrees BTDC . I am waiting on a twister manafold and have performed no porting or stuffing mods. She just seems lazy to me also. It always seems to have slight idle issues. About 2500 RPM is the best I can get. Compression seems very strong and little to no bleed off. Dual rings. Run time is only about one hour. Your suggestions are always welcome. Thanks - Al