boost gauge isnt really necessary.. but its always good to know how many lbs your peaking at... the next step gauge would be air/fuel ratio... with more air.. your gonna have to make sure you have more fuel to richen the mixture... more air/less gas equals BOOM.. detonation isnt fun.. the very important gauge to consider is EGT Exhaust Gas Temperature gauge... like on my truck you shouldnt be over 1500.. thats too hot.. thats another sign of running lean... the motor needs more fuel to cool it down... blow off valves will work on a s/c.. but it has to be centrifugal... not roots type... not necessary anyway... if its roots type there is a valve that knows when boost is present or not... when boost is present.. the valve is open.. but when u letoff the gas.. the valve closes so air does not go backwards... an intercooler also really cant be used on a roots type because they are pretty much bolted on and replace your intake manifold.. it would be major hard/waste of money/time to try and stick a intercooler between the s/c and the top of the motor... my s/c would also raise and i'd need to modify the hood as well... ever consider a turbo? u can get more boost that way.. :thumbup:

btw all the facts i use are based on my engine and most likely differ from yours :thumbup: