I agree completely Frank.
The one exception to the rule though would be replacing the KE-jet system with a free flowing stand alone fuel injection system.
That indeed IS sort of a "freebe" modification as it won´t affect motor behaviour in anyway but still push performance up by quite a margin.
You´re very correct in that people in general seem to believe that tuning the 16V is just a matter of turning a few bolts.
Of course it´s not.
The tuning of ANY engine comes down to;
1/DYNAMIC compression ratio
2/Total system flow
One specific of the 16V is that it´s a relatively "slow" burner.
Ie;It has a rather slow flamfront by todays standards.
Thi leaves us with an engine that produces a fair amount of power,but it won´t run especially "clean".
But..as stated...the by FAR most cost effective modification that can be done to a more or less stock 16V is the install of a stand alone EFI.No two ways about it.
Camshafts often come up when discussing tuning.Dbilas,Cat,AMG and god knows what else.
The thing here is...
Camshaft choice will affect the closing of the intake valve.
Hotter cams will make the intake valve close later in the cycle.
Look above...
Tuning is about dynamic compression ratio.
If we have a given static compression ratio and we close the intake valve later the dynamic compression ratio will drop as due coarse.
This brings with it that the so called Bmep(cylinder pressure) will drop as well,and that in turn makes for a weaker motor.Less power IOW.
Of course,if we install SLIGHTLY hotter cams,especially if we do so on a closer lobe centerline,we can get away with it,but ANY larger steps in camshaft choice HAS to be followed up by other pistons rendering a higher static compression ratio.
If not,our new superduper camshafts will only make the engine lose performance.
Another "freebe" mod would be a better flowing exhaust system.
Only drawback to that is an increased noise level really.
Diameter of the piping can very well remain stock for a stock engine,but the number of mufflers should be reduced as these indeed ARE restrictive to follow suite with mercedes philosophy.
A fair guess is that a car setup with a stand alone that´s been thoroughly maped that gets a free flowing exhaust will gain something like 7-10hp in top end power.
Porting and polishing of the head is completely detrimental until you start reaching the 270-280 mark if you ask me.
People that are "in the loop" put WAY to much emphasize on head flow IMO,but none the less the flow of the 16V is what sets it apart from most other engines.The flow of the OEM head is out of this world really.
Take my word for it if you want,but leave the head alone until you´re really up there power wise.Head will flow around the 350cfm mark@14mm of valve lift.Google around,and you´ll get amazed of how good a flow that is!!
One serious hinder to performance though is the intake system.
It has WAY to long runners to suffice when you pass 5 grand.
Measure if you want,and you´ll see that the intake has runners inxs of 500mm reading from the valve seat to the intake trumpet end.
This lenght should hoover around 330mm for a 7500rpm shiftpoint.
A new intake will most certainly wake the engine up and make it MUCH more fun to drive hard.
Hedder system...just leave it be.
It´s of extremely high quality and it suffices a looooooooong way..
Some install the heftier 2,5 pipe on their 2,3 engines.This is a sure fire way of losing TONS of mid range torq.
The 2,5 pipe is large even for the 2,5..
The 4-2-1 setup from the factory tends to emphasize midrange-which is exactly what we want for a street motor.
..and then...supercharging.
Compressors.
These can be divided into two main categorys.
Postive displacement and radials.
PDs are of roots or lysholm type.The latter one being more efficient by its design(Rotor screw)
Radials are often Vortech,ATI,Schorock aso aso.
PD superchargers work from the bottom up,and radials work as sort of a belt driven turbo.
No matter,the 16V will partly due to its massive system flow really shine when put under pressure.This works,end of story.
Turbos then.
This is where it get really interesting if you ask me,but expect a LOT of work.Is it worth it?That can only be YOUR decision....but you know what i think
Power wise..the sky´s the limit.For real.
My new engine for instance is something i setup to take inxs of 2 bars of boost,and if my calculations are right...that will push us beyond 650PS...
es macht wenig Sinn einem runtergenudeltem Motor der 200 000 Km runter hat und unter Leerlaufproblemen leidet nochmals das Rennen beibringen zu wollen....einen alten Mann läßt man auch nicht mehr Rennen oder versucht es ihm beizubringen 
Erlebnis eintreten wenn der Motor einfach nur mal die normale Leistung bringen würde, so gebe ich zu bedenken 
) und nicht zuletzt wird es einem ein großes Loch in den Geldbeutel reißen 
, für das man sich in einigen Fällen ein Fahrzeug kaufen kann....das einfach mehr Leistung in Serie hat 
Effekten kommen.
...beim nächsten mal gehts um das Elektrohydraulische Stellglied 
