To start out I have a 1999 miata with a racing beat axle back and a resonator delete via a local exhaust shop. This seems to have started when I deleted the resonator in my '99. After this, when the exhaust is cold (coolant/oil temp don't seem to matter very much, if the car has had 15 minutes sitting it will make the noise.) it has a rasp/rattle/**** honda noise starting from around 3k revs to 6k. My best guess so far is a piece of weld floating around in the muffler or the muffler falling apart. For shits and gigs one day I took off the muffler and didn't notice the noise and when I put it back on it didn't make the noise for the 1st time I drove it afterwards. :dunno: I'm thinking this may be something to do with the muffler but I'm not sure; do miatas usually sound rice after a resonator delete or is it something in my muffler causing this sound?