Can a Apex'i multichecker LOSE precision?

[HaLo]

Just a quick question...
Can a Apex'i multichecker LOSE precision?

I am asking this because I took out my 240sx with new engine and T25 turbo in the last few days and I have been getting some interesting readings. While my speed, rpm and timing do not seem off, my car has been making CRAZY power at 7psi.

Last year, on my T28 with 15 psi, the maximum reading I had managed was around 285ps and my dyno run at 15.5 psi gave me 283.7whp. So we can assume it's precise enough. The Apex'i harness is welded in my current harness, and it has not changed. The engine and turbo did change though.

Yesterday, I read peaks at 321ps and 298ps, the day before, 317ps, all at 7 psi with ~40F outside temperature. The car does feel quite powerful, but my butt dyno cannot be accurate, since I haven't drive my car since August 28... So could the Apex'i multichecker lose precision?

Anyways, I'll be putting the car on a dyno in the next few weeks to see. Hopefully, we'll get a good reading of this.