Thermal under suit

I have just brought my first under suit (Trakker Elite) its look like a track suit.

i always wear a bib & brace leggings and jacket in the winter mounths

My question is when wearing the under suit do you where trousers over the under suit legging as well as a bib & brace or just the under suit and bib & brace

I've done both in the past although I prefer without the trousers as it feels less restrictive and the idea is to let warm air pockets build up between the layers.

If the layers become so many that they start to feel a bit tight it defeats the object.