Modding a E55, the in and outs?
Batteries (both of them)
Key-less Go handles
Pano Roof Motor
Rear Sunshade Assembly
Brakes
Supercharger Bearing
Clogged cats (both!) -- ended up getting Kleemann headers
I fixed pretty much all of the above, except for needing an exhaust shop of course for the last issue. That will save money, but you will still get raped on parts. Be prepared...

im getting a pretty good picture that the E55 might not be the best choice for me at this point.
Maybe look at an Audi S4 or M3? They are much more fun to drive but clearly not as powerful. Not trying to scare you but keeping it real.
not really a big fan of audi, have heard and seen alot of horror stories happening to family and friends. the M3 on the other hand does seem very enticing, you are referring to the E92 M3 right? though i did drive my cousins M3, and it seemed really really gutless, no get up and go from light to light, was kind of disappointed with that.
Get the best UNMOLESTED car you can find for $15k and save the rest of your money for gas, tires, insurance, and maintenance.
http://www.ebay.com/itm/Mercedes-Benz-E-Class-4dr-Sedan-/131572131310?forcerrptr=true&hash=item1ea24f65ee&item=131572131310
Mercedes Benz E Class 4DR Sedan | eBay
That fleabay special has over 70k miles on it...not certified, who knows what else

Also HERE
The Best of Mercedes & AMG
2. Heat Exchanger (pick whichever you like) - doesn't add power, just sustains power by added cooling
3. Pulley/Tune - the S/C pulley with a tune is awesome
4. to get to 500HP - do the 82mm throttle body
5. and add some Kleemann headers (or any other headers)
6. don't forget to get a set of cooler spark plugs
7. Cooling tank (only if you see sustained high-end runs - honestly it's just adding to the H/E capacity...
8. get some good tires LOL
Buy a higher mileage car with service history for alot cheaper cuz of the miles and mod it how you want and you will have plenty of money for repairs IF necessary.











