When it comes to flying jackets, I would advise getting one made to measure by someone who knows how they get used in cars. As Steve says, the standard 1" pile of an Irwin makes the jacket very bulky, plus the standard arm cut means they can be a bit restrictive.

I got Cirrus to make me a B3 with ½" pile sheepskin, and It's just about perfect for me, but sadly I think they are no longer in business.

Tim H.
1986 4/4 VVTi Sport, 2002 LR Defender, 2022 Mini Cooper SE