Voltage problem after GTM SC install

zuperman 370

I just recently installed at GTM stage 2 SC on my 7AT 370z, it seems that i am having problems with the voltage now. The safe or regular voltage that the 370z should be operating at is 14v, 13.9 or 13.8 if it dips, when I turn on my car the voltage is at 14.5 or even 14 so its normal, then it dips down all the way to 13.4 and 13.2v and stays like that. I check all the earths, but all seems good, battery is brand new as well. Please guys any kind of help on what you might think the problem would be or things i should check for when a problem like this happens, could it be a weak alternator or a lose wire some where, and help or advice i can get for you guys would be much appreciated