need help hdj100 fuel consumption issue

2001 hdj100
Hi all, I have gone from around 11.5 l/100 up to around 16l/100. at 11.5 / 100 the vehicle was standard. Since fitted 3" exhaust, chip and snorkel and gone from 275 to 285 tyres (no roof rack or any other wind restriion). I first fitted the snorkel and then the exhaust a short time later (within a week or so) therefore did not get a measure on consumption at the time. I do know it went up before the chip went in. I have turned the chip off with no difference leaving the snorkel or the exhaust.

Exhaust is a 3" manta turbo back, I have never known an exhaust to increase fuel consumption.

Snorkel I am a bit sus on, it is not an ARB yet a similar design. Where it comes through the guard it is at a 90 degree angle, I am thinking this possibly could be restricting airflow. I have disconnected the snorkel (removed the rubber joining hose) and possibly made a small difference also the spiral bit has been chopped out of the existing airbox entry plastic pipework, another possible issue?
keen to know what people are getting with 3" manta system, tunit and snorkel so I can compare to see if I have an issue or not.