Audi A5/S5 Airbox. 3.0Tdi fit 3.0Tfsi?


Registered User
Constructive criticism is welcome. But if its simply something you wouldn't do to your car then don't tell me.

Since I am getting an MRC remap in a couple of weeks I have been looking at the modifications that they do to the standard air box.

I think they drill holes to open up the blanked off intake at the bottom of the box to let more air in, if anybody knows what else they do then please let me know.

My thoughts are the air box from the 3.0Tdi looks damn near identical to the one used in the S5 3.0Tfsi but already has the intake at the bottom open with a snorkel attached, all be it with a valve flap in place so it only opens at WOT. I believe this flap is often removed so extra air is in the box at all times.

I would also like to cut open a bit of the top of the box to let more of the induction sound out but not too much as it will upset my other three quarters(AVE ref) I have seen a thread where this was done and it managed to keep a stock look but let out just a bit off sound.

I have read all the arguments about heat soak.


Any thoughts on fitting the Diesel box is appreciated, I didn't want to cut up my original box but did fancy getting a spare box to experiment with.


Registered User
I'm fairly sure they are the same. Latest box for diesel is 8K0 133 837 B and that for petrol is 8K0 133 837 Q. The snorkel in question is 8K0 129 604.

The only mod that MRC do is to open up that blanked-off hole. Go for more if you want, but it is likely that the only addition will be noise - the available evidence suggests that even boxless installations don't produce any more performance - that's why the next stage involves porting and/or larger TB.


Registered User
Probably not much help to you, but... First thing i did on my 3.0 tdi was remove the butterfly flap at the bottom. Will add a tad more noise