What's it like to drive? One word. Amazing.
You feel the Mugen's extra shove right throughout the rev range - even at low revs, it feels much keener to pick up the pace. However, it's when the needle sits at the opposite end of the rev counter that the difference becomes really clear.
In a normal Type R, the engine gets stronger the harder you work it – there's a small but appreciable surge in acceleration at around 5,500rpm, and it keeps on going until you hit the rev limiter.
Spin the Mugen's dial to that magic number, however, and all hell breaks loose. Those huge exhausts start to bellow and you're propelled towards the horizon with the ferociousness of a Mike Tyson haymaker straight to the chin.
Arrive at a corner and things get even better. The steering has a bit of initial deadness, but once the car starts to turn, it does so with lightning speed.
You have to be very accurate with your throttle foot through bends, because the slightest movement of the pedal has a big effect on what the engine's doing, and that can unsettle the car. Get it right, though, and the Mugen's grip levels are unbelievable. The rock-hard suspension means the body stays totally flat in corners, too.
When the tyres finally let go, they do so progressively and controllably. However, the steering seems to have lost a bit of its feel, so you don't get a lot of warning when those moments are coming.
Still, those new brakes are sensational, providing monumental stopping power with no apparent loss of brake feel.
In short, the Mugen is quite an experience. It's focused and it's uncompromising, but if you treat it like it should be treated, it'll have you giggling like a fool.