The Peugeot 205 has great control even pushing it to the very limits, but at 650PP it lacks the acceleration of the F1 and GT and can fall behind if you don't keep it WFO through every corner.
The Nomad Diablo will, without question, blow the doors clean off an F1 or GT. I have a good tune for Nomad in the B-Spec 650PP race but it will work well for a human driver as well. My B-Spec driver wins Suzuka 100% of the time with Diablo, even if he's having an orange down arrow day and he's up against the F1. Once you get the suspension dialed in it turns just as well as any of your opponents and then that 850hp will go to work and win the race. I don't have a 2J but as far as I'm concerned for 650PP races I don't need, the Diablo is already a pretty much guaranteed victory.