new work truck has 180 ks and is a bit sad, i have shelved the mufler, blocked off the emmissions pipe, cleaned the throttle body and int cooler and tinkered with the adjustment on the turbo valve(i can now get up the hill to home in 2nd gear) what does this valve do? i live near mapleton and lots of hills td5 just not cutting it . need good deisal mechanic to sort my t4 out.....help