Check out this thread:
Bowden Cable Adjustments
We have the same model car so it should be exactly as shown in the pictures. The Bowden Cable adjustment is easily accessible in our car. It is in the driver's side beneath and to the back of the throttle linkage. It should have the characteristic orange bellows sleeve covering the end of it. I can actually turn the adjusting nut in mine by hand. Just keep track of how many turns you have made and in which direction. If you loosen the 13mm adjusting nut, it will delay the upshifts, which is what helped in my case.