was running 18/46 on marder ,now 22/42 and the top end is great,for big fields, i don't seem to loose as much bottom end as i thought.today raced my mates marder which is also 29cc with same ehxaust and they were always equal in straght line speed , they both left the line together and got to mid speed kneck and kneck but as soon as my engine hit top revs and jetpro came alive it left it in dust! you got to remember that when u run 18/46 you get wheelspin, thats why i kept up with him on initial accelertion,but still got a bit of wheelspin myself but more controllable.It would be a waste of time in small spaces as it takes abit longer to hit top revs,try it,youll be surprised of how little bottom end you lose if any due to better traction.