I was full powered on my 9 struggling while my friend was cranking on his 7.
Ask your friend to take your 9 and you can take his 7
If you are cranking on his 7 and he is struggling on your 9...then your 9 is the problem
But if you and your friend are doing equally well...or if he stills cranks and you struggle...
....it could mean your friend is more efficient at kiting than you..plus he may have a better board
By the way please describe his board and yours
Are you on surfboards....strapped....strapless....thruster...quad...width..length....etc...
Many times the board + someone more experienced makes more difference than the kite itself
Do you both weigh about the same ?