How well should sports leathers fit at first?

I'm off to buy my first 2 piece suit this weekend and was just wondering about a rough fit. I'm a bit of a gym freak so i'm not the average shape, at 6'3" with a 43" chest and 31" waist i'm thinking i may have to buy separate.

I tried on some alpinestars stuff last weekend, specifically the TZ1 jacket and found the 44" chest to be a little short on the arms but well fitted around the chest and the 46" to be fine on the arms but a little too big around the chest. How much can i expect them to stretch? I was under the impression leather should be as well fitted as possible as you don't want it moving around on your skin when you fall. Neither jacket restricted movement and i could probably get a jumper under the 46, not the 44. Unfortunately there wasn't a 42" to try on (my original thought was to go for the 42 and stretch it out).

As for trousers... well, i've never put on a pair of leather trousers so don't even know where to start.

Just a little confused about what i should be aiming for my first fitting, i'll of course speak to the lovely people at collin collins but was just wondering if anyone else could share their experiences / had any good pointers.

Thanks

My alpinestar leather pants where a really snug fit! I could just barely squeeze into them, this was reccomended by the guy in the shop who told me to walk around the shop for 5 minutes, after the 5 minutes they fit fantastic! Your body heat will soften the leather. My jacket is fairly snug too, but i can get a jumper underneath it at a push.

You need to go with whatever feels right. I must have tried on 10 leather jackets before I chose the TZ1

They should fit pretty well, I'd rather put a fleece over the jacket than worry about something underneath. Except maybe thermals.

When I buy my leathers I make sure that I can pnly just squeeze in them, after a few weeks they will stretch and will fit just nice.

why not get made to measure leather if you have the money for alpine stars you have the money for those. made to measure are of just as good quality and just as if not more safe. they will even personalise them for you