Just for reference...I'm not a strong guy...and I managed to squeeze a 650 belt on there...made for 2.8"-3.1" setups...without an IC. a 658 should be the belt for a basic 3.4" setup if I remember correctly...and it should be a snug fit. Plus..if you think about it.... a tenth of an inch is just an extra tug on the belt when re-installing