BEst fitting with Manual Boost Controller?

[umpkin]

b and c look to both be bleed valves, these give you slower spool up and boost spikes, these are the worst boost upgrades these days.

a. if its a bleed valve is same as above, but, if its a dawes device with spring and ball, these are one of the best without going into electronic controllers. faster spool up, and less spike.