Not Ranked
I have had both the QT SFI rated one and the non-SFI rated one. The SFI rated one is heavier than the non rated one, and targeted more towards racing where the likelihood of a flywheel/clutch/pressure plate disintegrating is much higher. Both of them were easy to install and did not required any shims or adjustments. The non-SFI rated one is plenty strong enough to handle a street application.
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