I have your added idler pulley with your special spacer!
It's something else that's causing the belt to not be tensioned...
Previous to the SC build I had lightweight underdrive pulley at the crank and overdrive at the alternator, I had those removed for the SC build.
The shop had to remove the alternator to install the pulley for it. Is it possible that the alternator had brackets that let it be moved by 1 or 2mm? Maybe they didn't position it perfectly, which didn't cause problems when the car was NA
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