Good to see you posting again, rad.

The NW single CAI and Eurocharged tune is a great combo for the Limited. Injectors, as mentioned, won't hurt but certainly aren't a must, and tuning them to have good day-to-day drivability is difficult.

Another mod that is free, is the removal of the baffles in the elbow under the MAF. Be warned that the clip on the connector that attaches the MAF to the elbow can be a pain, but aside from that it's a great mod good for ~10 crank horsepower. Mercedes only put the baffles there to quiet the intake...

There is a guy on ebay selling the MAF/74mm throttle body combo for roughly $225... This would remove the bottleneck between the NW intake (3" single pipe) and the inlet to the intake manifold, which is 74mm.

All of these mods combined should net you a fat torque curve and ~50 crank horsepower. EC tune is good for 23 crank hp, NW single is ~15 and the other MAF/TB/elbow mods should net ~10 combined.

Basically, ~$1,000 for 50hp and even more gains in the mid-range. The throttle response is also greatly improved.

An aftermarket muffler of your choice, if you can stand the drone, will help you get 5-10 HP on the top end. Deleting rear cats is worth ~5hp on a Limited, some deem it a waste to worry with.

Evosport sells a pulley kit for the 3.2 M112, and those run $300-ish and should net 10 crank-hp.

With every mod listed above, you should be sitting at ~280 flywheel horsepower with a mod-specific tune. It would result in a peppy little car that would be 150% more fun to drive. Should be low-low 14's in the 1/4.

Beyond those basics, things get expensive for each additional pony.

Last but not least, there's a turbo kit a-comin'...

Hope this helps.