I ran a dumpvalve up until a months ago or so and there IS a difference in the way the car respondes! Its so much smoother on gear change ,no jerking ect
My s2 is running 12psi (159bhp) and i could hear chatter(Still running Mfi) over the DV so i took it off and it sounds so much better!
Before anyone says " Ya metering head is fooked!" ive had it checked out and its in perfect condition!!!

My advice to everyone is take off the gay dump valve unless its really needed or your that desperate for attention that you need it

Nick