Im running 14/46 now.
Off the line, it's quick enough at that. Even two up on occasion.
Top end: it's about 125. To be honest, windblast for long periods gets a bit tedious in triple figures so i'd rather have the use of low down punch anyway. I've no motorways within a zillion miles of me so dont feel the need for it. If i did though, i'd probably leave it as 15/46 or 47.