10mm top gun leads would be fine and most effective, the leads themself dont produce power however they help you cars other mods perform better, therefore most people think they are cr/\p because they fitted them and nothing happend, you need to use them with a good set of plugs and other mods to see the difference.
for eg.
a stock engine with 10mm leads will only improve slightly
a supercharged engine with 10mm leads will improve drematically compared to a supercharged engine with 8mm leads.
catch my drift.
therefore when someone says 10mm leads are cr/\p and do nothing just laugh at them coz they dont know what they're talking about.