I have a 1990 BMW 525i, i bought it used recently. Seems to be a great car so far, but it is very loud, the exhaust note is deep, real deep. It's not tooo loud as a driver, but passengers in the backseat complain (lol) and when its started, it can be heard in the house. (the depth of the tone, not necessarily how loud it is).
I noticed that it had a K&N performance air filter. I dont think the box was changed (but im not sure either), just the filter. The previous owner said that it did bring in some noise though.
My question is just how much noise can a filter bring in? If I were to buy another filter, would it be noticeably quieter? Would a fram air filter do the trick (since its the most widely available).
The car really quiets down at about 4k RPM, and the idle is the loudest part, even louder idle in drive and as it revs more it quiets down. -- just some background info incase it helps.
Your time is greatly appreciated.