The before only got to 387 horses at 5967 rpm. The operator blamed the fresh air installation, meaning they couldn't get enough air in the engine to get to the MB advertised 421.
They did add 21 bhp to the total and promised a free run once the dynostar was replaced at the end of this year.
I can only hope that these 21 horses will also be there in real life at the Ring.
Stats will follow.
Oh, and I haven't noticed any extra performance, yet.
As in the next post, question to be asked: BHP at flywheel or WHP at wheels? If the former, then get the calculation they used as this is very low indicating something radically wrong. If the latter, then the 387 is high - either shows perfect tune throughout, or it is the figure with the new chip. 55 chassis dyno figures are usually somewhere around 360+.
This is not at all bad - 360 or 390 at the wheels, IF all went onto the tarmac would give a 1300kg car blistering performance! Unfortunately not so with the SLK! Unless this 387 is calculated at the flywheel, I would urge you to comcentrate in getting the chassis right so that the maximum can get to the tarmac - get the geometry spot on (go the full hog and add some adjustable arms etc) and use the widest, most worn out tyres possible. This where your better times will come from.
I do get annoyed o some other threads where the demand is power, power and power! 'i want a twin turbo V8' - why? 50% of the power will just be useless! The other annoying part to this is the scourn poured on the SLC43 'because it is less powerful' without giving any thought to what is happening to this power. 'The SLC43 is not a proper AMG' nonsense! it is maybe more of an AMG than the 55! - it is AMG who designed the engine mounts for it and redesigned the front suspension to stay on the ground better, resulting in better handling and consequently better track times, wherever the track might be.
Anyway, how did I end up on this..! Back to the post, ask the dyno people exactly what the 387 is and how they arrived at it. If flyweel - get the engine checked quickly! If wheels, fine tune the suspension and tyres - take a couple of runs, but some with a weight strapped into the boot to gauge the difference.
You say you have not noticed the extra 21. Assuming the engine is good and it is genuinely there, it will be difficult to notice such a small increase in road driving, but you should feel the car a bit livelier, no? Unless you drive the same track day in, day out, you will not see the effect properly. Bear in mind race preparationists tweek a bit here and there, take it onto a track and monitor where acceleration and braking point change by fractions of a metre, come back, do it all again, so only they will notice a few extra bhp.