Normal - 30mm/31mm
98/98.5 SVT - 32mm/33mm (measure out at 31.5mm & 32.2-32.5mm)
99/00 SVT - 34/35mm (measure out at 33.5mm & 34.5-34.7mm)
Even the largest SVT head ports (99/00) are only 34-34.5mm so SHOShop's 37mm LIM by itself would be a detriment to performance as the head ports would literally cut into the airflow badly!
Now on a 3L that had the head ports opened up maybe? However with even the Dual Honed SVT upper measuring in at 30.5mm/31.8mm I don't see them making a big difference by themselves!
For reference - a worked, triple honed UIM measures in at 33mm/34.3mm.
