If I were to run say 30% fuel would I get an increase in performance? what does a higher nitro content do?

Highly debatable topic. No doubt there's a difference between 10 and 20%, bu tthe difference between 25 and 30% is not noticeable. Also, going to 30% requires you to add a shim to your engine to slightly reduce compression. In europe we have 25% fuel available everywhere, and it's hard to find 30% (well it is in Greece anyway). In the US it's the other way around, as I understand. So if you have choices between only 20%a nd 30%, it might be worth shimming the mill and moving up. It's total rubbish though, that increasing nitro percent makes the engine run cooler. It either makes a negligible or no difference, as the increase in nitromethane causes a cooler fuel, yes, but also a hotter explosion. Also, the higher the nitro, the trickier it is to find the sweet spot when tuning.

adding nitro
basically increases the
amount of oxygen
in a given volume of fuel

at the minimum
you'll have to retune
you may have to
reshim and/or change glow plug heat
the engine, contrary to popular belief
will run hotter

but yes,
if you go from 20% to 30%
and make the necessary adjustments
you should see at least some
performance increase

More power but more expensive. For backyard bashing less than 20% is fine. Engine will last longer with lower nitro content.

+1

Well I personally easily notice the difference between 16% and 25%...never tried 30% though. Not even in the .21sirio...

I guess I'll stick to 20% then, mabey try 30% in the future.

After running over 12 gallons of 30% through my stock savage 25 engine before it finally started to wear out makes me think that 30% really isnt bad for an engine at all as long as it is tuned properly. My stock 25 would wheelie the savage on demand with 30% nitro.