Indicated MSL Altitude gain static system test

[moosepileit]

My RV-6 gains 40-60 feet indicated in a low altitude pass test at redline. At 70 kias it gains 20 feet or less.

I have the 1/2" diameter drilled rivet-type static ports T'd. I tried an IFR static cert at my first, to me, transponder check but the rivets at the time were not sealed from the inside. The actual ports leaked from the interior

They are sealed now, before this flight test and I'd like to try again for the IFR pitot/static.

The pitot side seems bang on in flight and rolling up tubing to 60 knots on the heated pitot tube showed tight over 10 minutes.

Without rigging up a self-created Static check- whadayathink?

Are those indicated altitude gains in the realm that suggests passing an IFR check? The altimetry and ADS-B in relative altitudes suggest the system is bang on at cruise up to 10,000' msl.