well, in general 3" piping is good to about 450HP...thats single piping...dual 2.25" is the equivalent of 4" piping...each pipe is only handling 3 cylinders after all...no reason to bigger than I need, its just added weight, I can always upgrade later if need be...as for water injection...I'm an experienced turbocharging person by this point and I agree with corky bell...there is no use for it in a well designed turbo system...I rebuilt an engine for a friend of mine because his water injection failed and he bent a rod...it was s-shaped when I pulled it out, I wont use water injection, alcohol injection is the way to go if you need to do that...but this car will already be running on ethanol from the start(same cost as gas here) for the 100 octane rating(plus I can always use gas if I cant find ethanol)...I already have a stand alone computer and its simple to switch between fuel maps and injector pulsewidths for the different fuels
in other news, I am trying to figure out a answer to my shock tower woes...my mustang is a '66...the SHO engine width is 22" from the edge of one valvecover to the edge of the other...which will fit between them...but the exhaust manifolds make the total width 23.5" which unfortunately will be located right at the worst spot...about an inch lower than the UCA bolts...this is an issue since I'll be doing the shelby drop later on....now the drivers side manifold I am not much worried about since the SHO v6 has its cylinder banks offset and the drivers side bank is far enough back that it shouldnt interefere with the shock tower....but the passenger side bank might be a bit trickier...I'll either have to A. do some imaginitve notching. B. Somehow make an exhaust manifold with a lot of tricky bends for the #1 cylinder primary or C. cut the firewall and move the engine further back or D. some combination of the above