Not quite a true rival, but the 1996 Storm Knight GT-4T could possibly get close enough to give the Scarlet a good scare.
The amount of time between versions has changed it up a bit, but while it’s more expensive now (at $27,160 @40% markup) than it used to be, the stats it boasts have also gone up.
0-60 in 5.3 seconds, 159 MPH top speed. 2.6 liters of MP-EFI driven Inline 4.
As said, not quite true competition, but, much like any of the Erin/Storm rivalry, they compete in different ways.