Boost spikes with BPV

Ever since I put in the Forge, I notice I get spikes of a pound or so when boost kicks in. My gillis is set at 15, and sometimes it'll go up to 17 for a second, dip down to 14 and then settle at 15. Never did this before the Forge, is this normal?

[This message has been edited by Matt S (edited 10-10-2005).]