I use my car on the street year round and on road courses during track days. In that context if I can't put down all the power in anything but a straight line at around 40 mph or so, that feels out of balance to me. For sure it feels stupid fun, and I respect the craziness of it, but day in day out it feels like too much. By that measure my oem stock 2011 GT with its 412 bhp felt like way too much power for the chassis. I've since done suspension, brakes, and tires, without touching the engine, and now to me it feels about right in terms of balance. "It's more fun to drive a slow car fast than a fast car slow." I like how you don't see that old saying much on a Mustang forum!