Shouldn't. Had Macsbug 6.2.1 on my original IIsi. Software version still reported 7.1. Just like how the boot disks for my Plus reported 6.0.7... On my IIfx, which has 7.5.5 and Macsbug 6.5.3 installed, the OS version number remains the same if I start up with extensions off.

I guess you could try. Boot the computer up and hold down the shift key. See what happens.

-J