What octane and brand of fuel do you usually fill up with? That curve looks a bit bumpy for a stock 335, this wasn't perhaps on 93RON instead of 95?
As George mentioned it could also be the plugs? Do you feel any hestitation on the road?
BTW what was the temp in the workshop when you dynoed, did they have all the heaters on or something, 29% correction looks high for the middle of winter?
Shaun the power is within standard ball park. :thumbs:
The graph is just looking rough, but it succeeded to give you the stock benchmark. Dont put the car through another stock dyno strain...nothing to gain from that.
Have it serviced, lekker tuned and then hit the dyno. Ask your tuner to datalog your car while on the dyno ( which he will do when tuning) now that data will be more useful to you then the dyno graph.
:thumbs: