I normally ride a 12m kite but I also have a 9m naish boxer (2005) which I never really use unless its 25+ knots

I find the 9m kite while very quick -does not have enough torque for me. The kite has 22m lines but comes with 7m extensions. I feel that if I use the extensions - the kite will be able to make more apparent wind and therefore usable power as each up and down will be longer... any comments? is this worth trying ? will 29m of line on a 9m kite be silly?

Reason I am asking is I would like to use this kite in 20knots - which I cant do atm and my 12m hyper type is ridiculously powerful in wind averaging 20knots +