Just to test it out, I used an otherwise stock Toyota GT 86 '12 on the stock SH tires with an automatic transmission and all aids off (just to eliminate variables) ... Engine was already broken in.
Stock Clutch:
0-400m (~1/4 mile) - 15.257s
0-1000m - 27.522s
0-100 km/h (~0-61 MPH) - 7.353s
Max. G-Force - 0.65G
Single-Plate Clutch:
0-400m (~1/4 mile) - 15.201s
0-1000m - 27.449s
0-100 km/h (~0-61 MPH) - 7.278s
Max. G-Force - 0.65G
Twin-Plate Clutch:
0-400m (~1/4 mile) - 15.162s
0-1000m - 27.393s
0-100 km/h (~0-61 MPH) - 7.217s
Max. G-Force - 0.65G
There definitely appears to be a difference in straight-line acceleration picking up a tenth of a second in the 1/4 mile and, oddly enough, more than that in the 0-60 time.
I also tried it out on a Nissan Bluebird 1800SSS (also stock) on the stock CM tires with an auto transmission and all aids off. I took an older, low-power model because they tend to take more time between shifts to rev match, so I wanted to see if it would make a larger difference:
Stock Clutch:
0-400m (~1/4 mile) - 18.878s
0-1000m - 34.136s
0-100 km/h (~0-61 MPH) - 12.987s
Max. G-Force - 0.42G
Single-Plate Clutch:
0-400m (~1/4 mile) - 18.744s
0-1000m - 33.979s
0-100 km/h (~0-61 MPH) -12.809s
Max. G-Force - 0.43G
Twin-Plate Clutch:
0-400m (~1/4 mile) - 18.735s
0-1000m - 33.947s
0-100 km/h (~0-61 MPH) - 12.756s
Max. G-Force - 0.43G
The peculiar 1/4 mile time difference between the single- and twin-plates is simply because it shifted AFTER the 1/4 mile mark with the single-plate whereas the twin-plate shifted BEFORE. Definitely a very noticeable difference in terms of how quickly it shifts between the stock clutch and either of the two aftermarket clutches with about 1.5 tenths of a second dropped off the 1/4 mile time and about a quarter second taken off the 0-60 time.