2000 S3 APY boost issues

[RaeS3]

hello,
I have 8l s3 apy, has been feeling a little down on acceleration. using obdeleven 1830 mb requested 1830 mb actual on a second gear followed by third gear pulls. If at 100 kph in forth I change down to third and wot I get 1980 mb requested 2030 mb actual, which feels more like I'm used to with the car, any ideas about why the difference?
thanks.

 

[RaeS3]

my fuel range is also worse than it should be, I'm suspicious of a possible exhaust leak. are these symptoms of that, I do have aftermarket exhaust manifold, dp and decat and have already fixed a leak between the manifold and top of turbo once before although the car didn't seem to be down on power then.