My PE #18 has an exhaust noise resonance in the 2800 - 3100 rpm range that is very annoying. It was noticeable since new, but becoming much more noticeable with more miles (now at 2000). It diminishes some as the engine warms up, but is there at all times, and in any gear. It comes from up front, and can be felt in the floorboard. My guess is that there is something not tightened properly, or parts touching that shouldn't be, or a bad rubber isolator of some sort.
Does anybody else have this issue?
Alvon Elrod, #18 White, no sunroof
1970 Fiat 124 spider