compression and leak down results

[SteveG]

Did a comprehensive health check on the motor in my newly acquired 87 325is. Nice one owner car with 180k miles. Not sure if this motor has had any major work done to it.
Run smooth, no noises or smoke.
Cosmetically and mechanically well maintained

Would like any opinions on whether to rebuild/refresh this or go with it as is.

Here are the results of compression and leak down:
#1 165 15%
#2 145 14%
#3 150 11%
#4 155 11%
#5 150 18%
#6 145 8%
Planning a few mild performance upgrades- lightened fly wheel, exhaust header and free flow exhaust system, ECU chip (any addl. recommendations appreciated).
Thanks!

[ForcedFirebird]

Did you note where the leakage was? The skewed numbers could be rings, or valve sealing. When doing a leak down, we typically note where the air is escaping. During the test, the throttle body should be opened, smoke in the tailpipe, and the dipstick checked. If air comes out the exhaust or intake, it needs a valve job, if it comes out the dipstick, that cyl ring set is compromised.

[SteveG]

Thanks for reply, cylinders 1,4,5,6 had slight valve leak, cylinders 2 & 3 valve and minimal piston leakage. In your opinion, would this motor require a rebuild, valve job, or ok to use as is. As I mentioned, it exhibits no smoke, overheating, unusual noises, or driveability issues.

[ForcedFirebird]

If you are fin with it, then it's not "out of spec" with there being an ~8% difference across the board. If you do a valve job, the engine will wake up a bit. I dyno'd a tired m20b25 that had 145psi across the board and it still managed to make 145whp. When they have a fresh valve job they are closer to 155, and will see 180-ish psi cranking..