what do you mean by mess up? when i went to install my pcm and hv3 when i had a gt i actually clipped off the top of my map sensor and when i would get on it, it was like in a safe mode or somethin and wouldnt downshift or accelerate like it should... i know you said maf sensor but i remember the trouble code readout said possible maf sensor failure also which made me check and clean the maf a few times in hopes of it working. just a thought. good luck with everything though