Do I need an SFI bellhousing?

Just to play devil's advocate, I think the old tech flywheels and clutches might have been some of the issue as well. There are lots of new cars out there that make a ton of power with stock flywheel housings, though I'm guessing the stock housings nowadays might be a little stronger. A new Viper will turn 11's in the 1/4 with a stock clutch and housing. Clutch tech has come quite a ways, but peace of mind is worth it's weight in gold. Better to not have to worry about it than to always be wondering "what if it goes?".