URS4- regarding Mass air flow sensors:
 

I have two 93's, and a 96. I am wondering if you have tried to swap a 93 MAF for a 94-95 MAF? The 93 is 3 wire while the 94+ is 4 wire. Is it possible to remove the sampling tube on the 93 if it is not possible to interchange the two?

And final question is what is your top of the line set up? This is what I understand it is so far:
- Velocity stack for airbox
- Velocity stack for MAF
- Bore and remove sampling tube for MAF / remove screen
- Stage 3 throttle body (what stage Tb do I have already?)

There is also hoses kits to be added to your list and I believe there is only one VS

Pre-93 is a 4 wire. 93 & up is 3 wire. The 93-95 uses part number...
 

078133471 for the MAF. With the introduction of the 96 model year Audi superceeded it's earlier version MAF with the 078133471A.

Only the "471A" MAF is suitable for machinging to Stage 3 specs. And yes the 471A model is a direct swap for the non "A" MAFs. In fact if you order a replacement MAF for your 90's today you'll get the "471A" MAF as the earlier versions are no longer available.

Top setup for all my mods is Stage 3, ie: Stage 3 throttle body, 3" silicone hose kit, MAF & velocity stack. Only a Stge 2 hose kit remains from that nomenclature as some people want to retain stock crankcase breather lines for emissions requirements.

Your throttle body is vintage Stage 1.

Here is my MAF part numbers and ETKA explanation:
 

<center><img src="http://pictureposter.audiworld.com/48795/massairflowsensors.jpg"></center><p>As you can see, the 93 had a vin split on the MAF. I have the earlier number MAF.

If you can find a way to get the early one to interchange with the newer one, great.

I don't have time for this right now, but when I do have the time I will definetly let you know. Let me know what you get for updates.

ALSO: what is the function of the additional hose kits? Just to filter the crankcase into the atmosphere?

Thanks!