Ford Shelby Mustang GT350R lap time at Circuit de Nevers Magny-Cours Club

Agree. In other direct comparisons the car was able to beat cars like the base Nissan GT-R R35 (570 hp) or the 991.2 Carrera S. Oh and it beat the M4 GTS in two direct comparisons with a hefty margin (Car & Driver Lightning Lap and Motor Trend Best Drivers Car) but here it lost over one second. Doesn't make sense.

It's 3 sec faster than the Mustang Bullitt there and you gotta remember that BMW doesn't release peak hp figures. Dyno tests reveal that the M3 Comp has approx 420 hp at the wheels so the peak crank hp is in the 470-480 range so it's not surprising that it has a slightly higher speed than the GT 350 R on that track.

Even with 470-480 range, that's still 50hp less. Keep in mind the GT350R will have much more corner exit speed, being earlier on the power too.

Quick check with Hot laps at Laguna Seca between the M4, M4 GTS, and GT350R. The top speeds at the top of the hill before the corkscrew were
111, 113, and 114mph. There is absolutely no way you can spin it that a GT350R would have a lower top speed than a regular M4.
https://www.youtube.com/watch?v=BuYet6Psh6M
https://www.youtube.com/watch?v=6JUSc5E_HJ0
https://www.youtube.com/watch?v=9kPRxiOB48Y

Making a judgement based on manufacturers hp figures is problematic for a number of reasons. Here are 100-200 km/h Dragy figures from AutoTopNL for the BMW M3 Comp and they ranged from 9.1-9.3 sec
https://www.youtube.com/watch?v=PkXx9qtF8no

Using the GPS mph readout with lap timer at Laguna Seca for the GT350R 62-110 mph took 6.5 sec and 110-124 mph took 3.5 which is 10 sec. It was probably hotter so maybe it could do 9.5 in better conditions. Bottom line is that this would explain why the M3 had a slightly higher peak speed even if the Stang was slightly faster out of the corner before the straight.

I clearly wasn't just judging my speeds based on HP alone. did you not see the 3 youtube links i posted?
why would you bother to go into eyeballing acceleration times when you don't know if the race track is flat, or not? Why put them in completely different environments to compare, when you have an actual test between 2 cars one after the other, M4 GTS and GT350R on the same track, on the same day, by the same driver? It's not rocket science.

Fact is, there's just no way that a GT350R will be several clicks slower than a BMW M3 at the end of the straight. Unless the driver totally cocked up the drive.

Why are you always so defensive? I compared GPS acceleration figures which speak for themselves and yes the figures i extrapolated for the GT350R were on the flat section of the track. Your statement does not prove in any way that the M3 comp cannot be quicker than the GT 350R as is evident by the acceleration figures and the stated peak speed on this track. Facts override bias :)