At a 11.0 to one air fuel ratio the car will most likely make less power with water/methonal. The engineer who set that system up will only let it run rich. If you pull the air fuel ratio down to a solid 12.5/1 power will go up with the use of water.
If my memory is correct that is a speed density system. If it is and it uses a 0-5 volt map sensor you can add some resistance to the MAP sensor out put and it should lean it down. This will also increase the timing. Under stand I have not done this on the SRT-4, but on other cars and added water and increase wheel horse power 25%. I beleive TurboXS has a program to change the computor signals for personal tuning. There web site is
www.turboxs.com.
My only true point is running that rich of a mixture may loose power with water/methonal. With water only may work better.
I will post a little information on the intercooler size after I do a little research.