What size are your intakes. I have 2, 3/4" intakes and a 2" exhaust. The highest spike I have seen was 312* after openi g the lid for much longer than I should have but is settles down to a +\- 10*. I cheat though I have ball valves on both intakes and the exhaust.
UDS (not so U) UDD, 22.5 OTS, Coming soon: mini UDS & double barreled RFS