hi guys im new to the site i have an 87 escort rs turbo,ive had it for 12 month and im on my 4th engine.im running 7psi boost on a standard turbo.when it starts boosting in 4th n 5th the engine starts pinking.my mate put his lm1 wideband on it n he says its holding 12.5-12.6 afr through all gears at 5500rpm n hes says thats good.ive ad it set up at re performance but its still pinking.i would be grateful for any help?thanks.