Best of both worlds

[dgp]

I would think you should only be concerned with intake valve build up on a direct injection application.

 

[Deuce]

I agree with dgp: intake valve muck is usually a direct injection problem.
Water/Meth inj may help you if you have a modified engine over say 13:1 static comp.
Does your local gull do e85 or only e10?

 

[07GTS]

water/meth is injected after the flex sensor so it wont be calculated for, and u will have to adjust for it in the tune and run it all the time, BUT u wont see any knock with ethanol and it actually works better then water/meth once it ignites in the chamber as ethanol actually vaporizes (petrol dosnt) which helps alot with cylinder cooling, ethanol dosnt always need more timing as it still ignites as quick it just burns longer u will need a dyno to adjust timing to best hp/torque as if u use the other method (NOT RECOMMENDED adjust till knock then take a couple out) as u will be well past max torque and start to loose power and do damage before u see any knock on ethanol, easiest way is to use the flex sensor and if ethanol is hard to get the buy a 200L barrel and store it and only fill up when u need to as it will last well over 12 months if stored properly, adjust the ethanol side of the tune to suit that and then it will work with both when needed, there was a test done in the US for all the fuels, race fuels, water/meth, meth, ect and the best fuel out of them all for power was ethanol at only 40% and only fuel that done better was e85 and e85 with meth so ethanol is a great fuel....