My take on it, different car (340i) but same engine & box. MHD stage 1. I only drive in comfort/auto, or sport/manual.
Comfort/auto. I was looking forward to having the gearbox 'lock-up' sooner, to give it a more responsive feel around town. Yes you can feel it locking up sooner but you get a very slight jerk when it does so, and the same when it goes up or down a gear. I now miss that smooth 'waftiness' in comfort.
Sport/manual. The gear changes are now smoother than stock. Which wont suit you if you like to feel that little thump you get when changing up at high revs.
Sport+/manual. This is where those thumps are, and you can specify how soft or hard you want them. Great fun when you're in the mood but I found it becomes tiring after a while and was glad to switch back to sport - so an unexpected bonus.
But this is where I can feel the benefit.
Having a stage 1 tune, before the xHP flash I often felt the the power was being reigned in at high revs, as if a throttle closure or something, and at lower revs the boost came in quite suddenly, not in a linear fashion.
Since xHP both of these traits have gone. The delivery is more linear and I haven't had the feeling of power being held back.
MHD has a tick box you select for manual gearboxes or those fitted with xHP. This removes the 'signal bending' MHD builds in to fool the gearbox into thinking it's receiving less power from the engine than it really is with a tune, which prevents it telling the DME to reduce the torque. I assume this is why my car feels like it now has a stronger, smoother power delivery.
I would rather have xHP than not, but I can't understand why some people rave about it. Can't really say it was worth the money. If I didn't have a tune, I wouldn't want it.
On top of the cost I was charged £7 odd 'currency conversion' fee, probably because I used a credit card to pay. Not sure if the same fee is appled when using a debit card.
