I just don’t want it to slow me down but at the same time give me clearance not to scrape the exhaust in turns.
Actually, I would say the fork extensions increase the chances of scraping the exhaust because you're tipping the front of the bike up which forces everything in the back to tip down. I scrape my pegs all the time with 3" extensions. My old Cobra Swepts had a nice flat spot underneath too.
Seems to me that giving rise to the front would just make the front higher, you haven’t lowered the rear, it remains the same. If anything the pegs would be slightly raised too.
Yes, but if you have a long exhaust and the tips point downward, it's going to aim them more to the ground after lifting the front. So there's more chance of scraping the tips of the exhaust.