If this solution were available I am sure it would require an intercooler for optimum performance, probably and aftermarket ignition, but actually engine bay / supercharger cooling would be of a major concern for me also.

Is there really enough room in the engine bay to do this solution correctly?

4.2BURNS

They're cheap, easy to install, and thermally more efficient than roots/twin-screw, but they don't provide enough boost at low-mid RPMs. For heavy street vehicles, like Audi's, roots/twin-screw is best (large torque gains throughout the entire RPM range). You would need an intercooler for this engine to obtain reasonable boost/power without detonating with the stock compression ratio and pump gas.

Have you seen any info on the MTM (AutoRotor) or APR (Eaton) supercharger solutions for the 4.2?

Here's all sorts of calcs for the 32 v ABZ engine, your enigne is 11:1....and centrifugal is the only way to go IMO.<ul><li><a href="http://forums.audiworld.com/a8/msgs/98631.phtml">My Supercharger Calcs</a></li></ul>

MTM originally developed their supercharger for the A8, and it's also available for the S4. There's a catch... it's $21,500 for the bolt-on 450HP version in the US. You don't want to know what the 500HP version costs (which requires internal engine modifications).

APR is working on a supercharger for the S4. You'll need to contact them to find out more info as it's not due out until mid Summer.

MTM - <a href="http://www.mtm-online.de/en">http://www.mtm-online.de/en</a>
APR - <a href="http://www.goapr.com">http://www.goapr.com</a>

I'm lucky enough to have an Audi specialist reasonably close to my house who's a pro at sport tuning. I phoned and asked about it a few weeks ago and they said 7-1, but I'm going to wait until my B7 is out of warranty before I go with the SC.

The MTM solution is incomprehensible. I've got an '07 A6 4.2 on order that I'd love to drop a supercharger on but hell, I can get the S6 for a cheaper price than the MTM mod.

Are the APR or PES solutions going to be more reasonably priced?