i decided to create this guide due to the number of guides showing how to do the bypass using the fpr as a tee point for the dv so to help with confusion i created the correct way to set the bypass up.
ok first open the bonnet and you will see.
then take off the engine covers there will be 8 twist/push in screws.
the part you will be getting rid off from the top of the engine bay would be the vac chamber which is held in with 2x 10mm screws and there would be one pipe coming off this going next to the dv this needs disconecting also.
once the vac chamber is removed and the pipe from the top of the dv is removed you should be left with 2 metal pipes with neither the dv or the vac chamber connected.
next step is to disconect the plastic pipe which goes to the airbox this is so you can move the metal plate infront of the inlet manifold.
next is to remove the 2x 10mm nuts ontop of the metal plate infront of the inlet manifold so the other part of the plastic pipe can be moved out of the way and also remove the two allen key bolts holding the plate to the manifold.
now there should be three pipes running along the side of the engine bay to the metal plate two will be coming from the vac chamber and the dv as you removed the other end off these before they can now be cut. there is also another pipe which is a braded pipe this goes to the SAI unit this can also be removed (be careful as the pipe that connects to this is small brittal metal pipe)
once removed the rest of the SAi pipe will look like so.
there should only be one pipe holding the metal plate to the car this pipe can also be disconected as it runs from the metal plate to the underside of the inlet manifold.
with everything disconected the metal plate can be reomved now and will be left with.
the box in the centre of the metal plate is the n249 which we will be disconecting and the other is the n112.
i found it easyer to cut the pipes to the n112 and unscrew the part from the plate to remove the metal clips holding the last bit of the pipe to the n112 to save breaking the nozzle of the n112.
now disconect all the pipes from the metal plate and make sure you remember which way the one way valve went i put a lil bit of tape on mine so i knew which end went which way.
with all pipes removed it should look like this.
now you need to get the silicone hose out and some tie wraps first connect the silicone hose to the SAI.
with that end connected connect it to the n112 make sure you have enough hose for when the metal plate is put back where you disconnected it trial fit to make sure it allways best.
now remembering the way the one way valve went connect the n112 to the 1 way valve.
then connect a small piece of pipe to the nipple to the underside of the inlet manifold which you freed up by removing all the piping the metal plate.
with the small piece of tubing connected put a tee piece in the end of the small tubing comming off the nipple then connect one end to the one way valve and the other end will be connected to the dv.
make sure you tie wrap the one way valve up so it does not dangle all around the engine bay.
now with the metal plate put back and the two plugs connected back for the n112 and the n249 you can start to put the engine bay back together this is what you should be left with (excuse the white tee piece this is the pipe for my boost guage.
while i had some spare hose i decide to change the fpr hose for some silicone hose.
with engine covers back on this is what i was left with.
size 5 Allen key
flat head screw driver
hook shapped pick
1 hour including taking pictures
Non only a case of disconeting some pipes and changing the pipe work over for new pipes.
£5 for 2m silicone pipe.
£1.50 for tee Piece ( although i had one spare so i did not need to buy this.)
£2 pack of 10 tie wraps ( Already had these in tool box so did not have to buy.)
What the Bypass Does.
eliminates the ECU controlling boost in which the ECU dumps boost unexpectedly resulting is poor control in car the Traction Control is not affected by this i tested this out on a field and yeh the traction contol still kicks in, the dv is more responsive and slightly louder, minimal throttle response inprovement, reduced risk of split pipes or boost leaks as changed more orginal pipes for silicone pipes.
hope this helps out people this guide is mainly for A3 Owners as welly has done a great guide for S3 owners this can be used for the A3's any thing i have missed please let me know.