Just recently bought an 05 sti with an fp green (recently built motor + all supporting mods) that was tuned to hit 1.6 barr. The weather in my area is a bit cooler than where the car was tuned by the previous owner and have noticed that i am having spikes of overboosting around 1.7 1.75 barr in higher load situations (higher gears, even cooler weather, sometimes partially being on the throttle when shifting, etc). The car only has a MBC (hallman pro) and accordingly i turned down the controller approx a 1/2-3/4 turn to attempt to keep the boost down.
Immediately i noticed that the throttle is less sensitive and that there is more lag in building boost, yet i am still managing to reach 1.7+ barr
1) why is it that despite turning down the controller i am still achieving the same boost levels?
2) is it normal to have the increased lag and decreased throttle response issues when turning down a MBC?