My mafs did this too, I bought a 5" Plastic plant pot, got it at home depot. 7 $.
Cut it in half, placed them on the back side of the filters, against the rad. When my fan was turning on, it would give my MAFS a weird reading. This fixed it.

OK some updates for you.

I smoke tested the car going directly into the inlet manifold and we have zero leaks. Pressurised the system enough that it was bellowing out the air filters.

Im going to go with the decats are causing a drop in boost and thus a drop in power.

Did you ever find out what the WHP is?

That's not exactly the way to think about this... you can make less boost, and more power, provided the mixture is timed to combust optimally.

BUT... if the mixture is blowing out too quickly (i.e., before peak torque is made in-cylinder) then VVEL timing tuning is in order.

Think of this in terms of optimal cylinder filling -- too much restriction is no good, too much flow is no good. It's gotta be just right.

That said, adding a mechanical "choke" is almost definitely less desirable than adjusting valve overlap.

pressurized the system enough that it was billowing out the air filters sounds like it wasnt pressurized at all. to do a pressure leak test you should have capped the exhaust, plugged the intake brought the piping up to the rated 10 psi to find leaks under pressure.

This makes sense. :iagree:

The problem I am having here is that no one has mapped a setup on this engine like this in the UK before. TDI who mapped it are VERY good but this setup I feel requires specific knowledge of the engine. I couldnt have asked any more of TDI, they went above and beyond on the day :)

I have sent Motion Lab a PM to see if they would be happy to remote in when the car is on the dyno to alter/tweak the map. Hopefully they will get back soon.

Can anyone else recommend someone who might be willing to do this? :tup:

I'll get my coat...

Do it again in the morning. You can tell im not on the tools. Ever.

I'm sure Alex and Todd will help out . They are very much stand up guys. They are remote tunning my car now and have helped me in the past with my Stillen SC kit tune also.

If the results show no leaks and the car is making the correct power then I would not worry about the PSI level. Remember that using less boost and making equal power just means the system is running efficiently.

But I agree with others, if you have major concerns you can always do remote tuning with a shop to look over the car.

the other bosst related thing to check would be belt slip, make sure the ensioners are tight but don't overtitghten them or you will blow out the bearings in the jack shaft and input side of the charger(or go cog belt drive)

As you can see it looks as others have had the Same issue you had... Maybe next time before you decide to go fi you will have some money put back for unforeseen things that happen...:roflpuke2::icon18::icon18:

I PM'd him and he was joking/taking the piss. Not that funny.

Ok, smoke tested the car, no leaks.

I spoke to Stillen who thought it may be possible that we are getting belt slip so I have got another belt, a 7PK2635. Going to fit it tomorrow and see if that effects anything.

Ok. Fitted the new belt and its made zero difference.

I keep reading threads both new and old of people with the same kit, 9lb pulley test pipes etc making 9-10psi boost. I don't understand why we are loosing 2 psi. There are no boost leaks so I am very confused. Can anyone shine some light on this for me or point me in the right direction?

This might be apples to oranges here, but my past turbo cars (Audi/VW) would vary 1-4 psi depending on weather conditions. When it was hot outside (80-90deg F) I could hit 24psi but when it was cooler than that it could go down to 19psi. Same power output but less boost. I've never owned a supercharged car so this may be irrelevant but remember it takes less boost to make the same power with cooler air