I don't think the 3.0 manifold will fit under the 190 hood, and I also think it has slightly smaller ports, which will limit top end power... not sure about the exhaust manifold ports.

...suggest you use a dial back timing light to map out the WOT spark advance curve with the vacuum line to the EZL disconnected and plugged. The 4000 rev torque surge may be caused by a lazy spark advance curve below that speed.

Duke

I'm certain the issue was in the ignition curve given it's tied to the EZL.

As for ports and what fits the 2.6 and 3.0 ports measured the same. We had a 3.0 manifold on a 3.0 in this car at one point and it fit but the egr blockoff was ugly and extra points of failure.

The air cleaner has never fit right on this car. The base is bent and that's an item on the todo list.

You do have a good point in figuring out the ignition map however. So I can get some empirical data.

Just note the EZL retards at 70C and 90C water temp so performance application has to remain between those temps. As mentioned earlier not real noticeable on a stock engine in road driving but very noticeable when you start chasing horsepower and watch it perform so very differently with a few degrees water temp. Out of the box in warm climates the 103 and most Mercs up to current models run around 90C daily driving. On the track KE3 needs to be around 80C or it retards the spark. I played with thermostats, aux fan switches and piped a water-methanol injector just to make sure I keep cold morning horsepower when I'm racing a GTI at midday and it's sunny. It cost like a grand and gave no benefit, but did prevent a loss which was the benefit and a huge one. There's this late model GTI R that gives me a go on the way to/from work sometimes and I match him in mornings, lose afternoons but now afternoons are like mornings and I no longer headbutt the steering wheel if I see him on the way home. Seriously, it's like 25hp difference in my car, cold mornings to warm afternoons before the thermostat and MW50 mods to keep temp at 80C when it's 38C ambient. That's KE3 for you.

The best maps in the export EZL units are the 740ohms ones for USA and Japan. If you get better results bridging the resistor or removing it then generally speaking it means there's something wrong with your EZL.

This is because the export EZL have a single fuel grade map. The Oz one is for 91RON regular unleaded using 260ohms and 89RON low quality unleaded when bridged. The US and Japanese one is for 96RON premium unleaded using 740ohms and will probably default to 89RON when bridged.
Only the Euro EZL with the dials at the EZL itself and at the R16 resistor (a dial instead of a resistor in the battery compartment), this is the only one which has better ignition maps available than the 96RON Superbenzine 740ohms. The dial EZL and only the dial EZL has a map for Shell Ultra which is the equivalent of modern 98RON ultra-premium.
The export EZL modules just don't have this facility. The 740ohms version is the best map available among them.

Now the reason you might get improved pull by bridging or removing the R16/1 on a 740ohms export EZL is because you were probably running the motor at 92C water temp and the normal running map retards at 90C. Now you bridged the resistor so it defaults to poor fuel grade and doesn't need to retard but the different map probably kills some horsepower at the very top end, since it's for 89RON unleaded when bridged.
Speculatively, but it's a rather educated guess. Been dikking around with mine for 5yrs cracking 240hp, half the battle been keeping the power gains under different conditions since that's what KE-jet is absolutely the worst at.

What I'm saying is the best ignition map among export EZL for stock motors is 740ohms.
Keep your water temp at 80C to maintain that map without predictive retarding to prevent engine knock due to ambient. It retards at 90C water temp, so doing something worse than the stock map would be better when it does that, but even better than that is keeping the water temp at 80C so it doesn't retard.
Trust me, it was worth the money I spent doing this even with the AMG EZL. It's the KE3 thing for not having a knock sensor.
It was a major noticeable difference street racing to get my water temp to stick under 90C no matter what.

As I stated previously in this thread, the most aggressive spark advance map according to my data (advance with RPM) is with the 750K ohm resistor removed (infinite resistance), and the least aggressive is zero ohms (resistor replaced with a shorting wire).

I posted my data in a thread started by me about ten years ago. The primary difference is in the low rev range and is supported by SOTP impression and a significant fuel consumption reduction around town. Since I only drive my 190 in the winter I am able to use 87 PON fuel, but get a little detonation with my usual 2000 RPM short shifts if ambient temp is above about 70F or the coolant gets up to about 90C in traffic, which I can "drive around" by shifting at higher revs

My engine usually runs about 80C in mild weather and I'm not aware that EZL retards the spark advance at 90C... seems kind of low to me.

Duke