jimnastic

When I first start the car, every time I'm between about 2500RPM-3000RPM the exhaust makes kind of a 'whispering' noise.. can't think of a better word to describe it . Anyway, usually once I get to about 4th gear, it doesn't happen anymore and won't happen again until next time I start the car again Does anyone know what might be going on? I have a feeling it might be because of that valve thing in the right exhaust pipe but that's just a wild guess cause I don't know what that thing does. I hope someone can help me out because it's pretty annoying

Thanks for your anwsers so far! I just thought i'd mention that the cord for the aerial comes out from behind the glove box and then splits into 2. 1 end goes into the back of my head unit and the other half goes into this box. So I assume that it is actually doing nothing at all because it isn't really connected to anything. Does that make sense?

Yeah, it's attached to the aerial cord and it has an aerial plug in it. I probably should've mentioned that. I just don't know what it's for and wether or not it needs to be there

Hi everyone, Just last week I bought my first car, a 94 R33 GTS-4, but the guy sold it to me without a head unit in it. So I went and bought a new one and when I was putting it in, I noticed this little green box thats in the picture. Can anyone tell me what it is and what it does? I managed to wire everything up and it's all working perfectly, but I just found it strange that this thing is sitting there doing nothing. I don't know a thing about car stereos, so I'm sorry if this is a really dumb question