Are you sure? I think you may not be reading the description of this part correctly. The Bosch diverter valve has a problem with leaking boost past 6 psi but, to the best of my knowledge, it is not a BOV/diverter valve as well as a pop off valve. Turbo systems control boost pressures through a waste gate and BOV/diverter valve. Some turbo systems have pop off valves for an extra margin of safety as do many positive displacement blowers in case of a backfire.

An update on my project. Spent the last 3 months trying to get fabricated a straight through silencer for the supercharger outlet to quiet it down. In the end I bought myself a mig welder and made it myself. Basically its a 5 inch diameter steel pipe 6 inches long with a baffle plate half way creating two 3 inch long resonator chambers. I lined these with fibreglass wadding and held it in place with a wire mesh. Its just like a straight through exhaust box. This worked well. I did the same for the inlet using 4.3 inch uPVC drain pipe but drilled a 2.5 inch uPVC pipe with hundreds of holes to create a baffle pipe to go inside it and lined it with sound deadening. I also fitted my K&N inside another chamber with sound deadening around it allowing a gap for it to breath with a pipe taken to under the front bumper for cold air.
Also I stripped down my supercharger to see if I could check it was okay internally, but it all seems fine and I sanded down the scratches on the vanes (lots of). This helped also.
Finally I added another Bosch by-pass valve so I now have 2 in total.
At last I can drive my car with the supercharger fitted. Its almost silent at idle and low cruising speed. The twin by-pass valves do their job well making a nice pssshhhh!! noise when I take my foot off the gas, just like a dump valve does.

It now goes very well now with lots of torque.

However, solve 1 problem, find 2 more.

Its still very noisy when I put my foot down, still screams.
My inlet temperature at cruise is 85degC/185degF and when I'm at full boost it goes up to 105degC/220degF. This is way too hot.
I'm also getting a lot of oil being sucked through the PCV breather pipes.
I've also had a smaller pulley made up giving me 3.2 times crank speed. I was hoping for 6psi as my previous pulley at 2.8 times crank speed gave me 4psi but its still the same with a smaller pulley. I'm probably getting belt slippage so I'm going to add another idler pulley to give the belt more wrap around the SC pulley. This I hope will give me the 6psi I want.

I've thought about adding a chargecooler, an intercooler is out of the question because of the plumbing required, but this will reduce my boost again so I don't fancy it.
I think the problem of my hot inlet temperatures may by caused by the bypass valves recirculating the already warm compressed air round and round.
Maybe I should just vent them to outside air.

My next step is to try and move the throttle body to before the supercharger as I've read this will make it quieter and I think reduce the inlet air temp.
However this is starting to defeat the idea that this was going to be a simple supercharger bolt on operation.
I've just bought a spare 3.2 engine and will try adding the throttle body from that fitting it before my supercharger.
I have noticed other people moving the throttle location and wondered if anyone can shed light on why and what difference it made.

Any ideas from you guys who have fitted superchargers will be of help.

Good job. My supercharger is alco very loud. I will need to try something like you have done.

Have you measured your air fuel ratio under boost? Very importand if you want to avoid rebuilding you engine.

I also had trouble with belt slipage. Just figure a way to tighten the belt and wrap it further around the pulley.

Your inlet air temperatures are very high. check the specs on the third graph on the Eaton site, http://www.automotive.eaton.com/product/engine_controls/superchargers/M45.asp
With 5psi boost, the max temperature rise would be about 100F.

I was also interested in looking at this graph with your statement that you are turning the supercharger at 3.2x crank speed ... or 16,000 RPM at a crank speed of 5000 RPM. I would expect that that would make some noise.

__________________
Jim Villers
190SL, 230SL 5-speed, 95 E320 Wagon, 01 E320 Wagon, MGB, Boxster 'S', 190SL "Barn Find"