VerrÜckt

The problem with your statement is the "if". The 710N's have no problems operating correctly. There is no boost fluctuation or leaking.

paulroad

Stock valves use a rubber diaphragm. As the age or in the case of added boost (chip/DiPP) they don't hold up.. under pressure. Spikes in your boost result becaus the engin is calling for boost and not getting what it expects and then calling for more. It finally gets it at a high point and then reduces the call..these are the spikes. Changing to a better Diverter..one that doesn't use a rubber diaphram will eliminate these spikes. Changing to one that is adjustable..like a forge (if chipped) will also smooth out the power delivery..not just eliminate the spikes.

VerrÜckt

The 710N's are designed for use on the Audi TT which produces the same boost levels as a chipped S4. I routinely test mine and I've never had a problem. I also run more boost than 99% of the S4 forum. It's quite rare to have a 710N unit fail.

To clarify, I'm not arguing with you. I have no problems keeping this to a civil discussion.<ul><li><a href="http://www.s4biturbo.com/art-dvtests.shtml">To boot, the response time of the 710N is quicker than the Forge.</a></li></ul>

paulroad

They do fail at times. I have personal experience with it as well as experiences of others.

But my story shold work.

With APR.. my acceleration was wonderful and delivery was a sudden rush. after a few months I noticed a spitting of the boost at times. I also found that at a continued hard drive with 4-5000 rpm shifts, the car would overboost (VAG Verified) and go into fail safe mode for a minute of so.

I investigated on the boards, and spoke to some heavy mod mechanics and the general consensus was to change from my stock 710B to the 710N or if $$ prevailed go to the forge adjustables.

I went the cheaper way to the 710N valves and they worked but still with a rush, but then after a month or so the same pattern started to arrise.. spitting delivery of the boost and under extreme conditions into fail safe at 4-5000 rpm shifts (3rd-4th).

This time I went with the forge valves and used spring # 2. The above conditons NEVER reappeard and the delivery of power was so stock like smooth.. but at a slighlty lower level of...hmmm..strength? than the 710N gave.

SO... one day I made the change in the spring to the lighter Green spings in the forge valves. And The strenght of power was back.. it was a great ride with the lower setting. BUT.. One day after waterfest at a light...with another car...

lets just say the fail safe mode came back right before I heard a certain lady scream.

My son has a heavy modded GTI.. and we would watch his boost gauge climb up..spike.. and taper down..like a roller coaster. He too switched to another billet style valve and this eliminated the probelem.