If you wanna run pump gas keep it below 155ish or so. That's what most people will say but I"ve had buddies run alot higher w/ pump gas and be fine, but no one will tell you that on here. As for timing +5 or +6 is fine IMO. If you wanna run race gas you could go all the way up to 200 or so, that's a tad high and unreasonable but you could. I'd say 175-185 is normal. 19cc or 18cc domes would get you there at sealevel.