Been though most of NAM and can not see these speifica symptoms.

I have had the supercharger off and back on, to inspect for problems due to whining, which turned out to be the belt tensioner. Replaced belt tensiner and put car back together.

Now I hear a howling/whistle-like noise ONLY under acceleration with these conditions.

A) Car must be in gear (any geaR)
B) More than light acceleration must be applied

In idle, I can not repoduce the sound under any RPM and either fast/slow reving.

Very light acceleratiol will not reproduce the sound. I can ease the car into higher rpms in any gear without the sound, however, if I give a little more throttle the sound appears thoughout the RPM band for the gear.

I am thinking (see image for numbers):

1) Maybe the supercharger connection.
2) The scoop air inlet
3) The bypassvalve is not closing all the way
4) The connection from the S/C to pipe that goes to the the intercoooler
5) The pipe attachments to the intercooler in/outgoing
6) The seal on the intercooler radiator style blades
7) the connections to and from the airbox.

Keping in mind this is under load, the additinal instake/sucking of air could potentioanly force a small gap in bad a seal/connection, creating this howling sound, ONLY under load and in gear.

You brilliant minds are envited for brainstorming sulutions and suggestions

P.S. Automechanic said chipped or bent S/C blade, but i forgot to ask if they had the car under load on a dyno. Doubt its the interior of the S/C or pump.

 

I've got a similar issue with my 05. Under acceleration I notice a whistle from the intake. Not a normal noise on a boosted car I'm used to. I don't have a boost gauge to check my boost but it sounds like there is a leak somewhere.

I only notice it under acceleration as well....it's not there at idle when I hit the gas.

 

I have had the same issue with my 2002 MCS since I installed an ALTA cold air intake and replaced the stock intake pipe (between filter and throttle body) with the Alta silicone pipe.

Same here: no whistling at idle or when I give 'er while the car is stationnary. Whistle happens under load, mostly at highway speeds when applying a little throttle. As soon as I back off, the whistle goes away. Whistle isn't present either when giving hard throttle while car is moving. It happens at highway cruising speed with very little throttle applied.

I have not noticed any performance decrease nor fuel consumption increase.

Funny this post showed up. I was going to ask the question, but MINIDK explained so much better than I could have

 

Glad but not for you, that I am not the only one with this issue. Wish I could throw it on a dyno type platform and pinpoint the sound. It sound almost like a sucking in on a hamonica

 

Wow, what a coincidence! I have the same problem. I recently replaced my intake with an aftermarket CAI and I intended to replace the induction hose with the Alta version. However, I didn't like the fit so I put the stock hose back on. However I didn't use the stock hose clamps, I used clamps from Home Depot with a 1/2" wide strap. I was thinking the whistle I got with mild throttle might be because the seal on one of the hoses might not be good. The stock hose has grooves in each end that fit the stock clamps which are only about 3/8" wide. I wasn't sure if that small discrepancy would affect the seal at the throttle body or intake enough to account for the whistle. I'm expecting a different induction hose in the mail which I hope will eliminate the problem, but I'm not too sure.

 

My experience with sounds like this come from turbo cars, and not superchargers. I don't have my mini yet.

But to me it sounds like a boost leak.

 

There are two differeent sounds getting described here...
The "Alta whistle" and to a much smaller extent most any CAI on a mini can make a bit of extra noise...well documented...It is louder with foam filters...and present with light throttle....other intakes do it too, but it seems most noticeable with the Alta filter/tube placement...
The first one IMO does sound more like a boost leak..but he also states the bypass valve is not closing.....air/boost is exscaping from it...it should close fulley...check the vac lines/spring in it...maybe wiretie it shut, and see if the noise goes away....