That's the same engine in my car. They are nice engines. However even with te same mods mine will always be faster due to the massie weight difference. Are they reliable? Very. Mine has been incredible. If you can pounce on it I would.
I'm sad it's the 540 with the issues. That's the one i would've wanted. The E39 M5 is tunable to over 1000 HP. Search for the "El Diablo" on the M5 Board.