Thermawrap Sizing

Purchasing the vest and jacket online but need to decide on the size.

The sizing from Montbell indicates 41-43" chest for the large and 44-47" for the XL. I'm at about 43" but short (5'7"). I'd have a base layer and possibly another thin sweater underneath this.

Large in Marmot and Arcteryx fit me very well.

Any opinion, and should I get the vest of the same size as the jacket or is it safe to size down one from the jacket?

Thanks.