Like iminhell stated , the PW can only move so much air , you can open the intake to the size of a coffee can and the exit to the size of a 5 gallon pail but if the rotors cannot move any more air ( and they cant ) then doing the intake and exh big wont helpPorting a blower does help! It helps with the bottleneck inlet/outlet and increases efficency. Cobras can get an increase of 25-50 hp depending on mods.
I have had 2 customer that did the porting and it didnt help but about 5 HP , a lot of time and cost for 5 hp
As for alki or water meth its a waste of time and a lot of cost and trouble , for the power your making I dont feel there worth adding , you NEVER want to add water meth and tune for it , its a small safety factor in that is can cool the charge a little but do not tune for it