You will certainly get less clamp load using non G40 bolts. Tps decided to supply me 9 G40 head bolts instead of the 10 I ordered so out of desperation I used 1 Gsf bolt. With all of the bolts torqued to the correct sequence I did an over checked with 100nm on the torque wrench and all the G40 bolts clicked off but the GSF bolt didn't and kept going.