anyone had a full 2bular system (incl manifold) fitted and then developed a ‘zing’ at around 3000rpm? something is vibrating? i suspect heatshield perhaps, any good cures?
It’ll be pistons rattling as they melt … running lean!!!
Zing or metallic rattling at certain RPM is a sign of detonation.
jfk - your really not helping owners.
^^^^ post never implied I was ?? ^^^^
What a Beavis !
What sort of silencer have you fitted? Jims track day version I recently fitted on my car was bigger dia than the Lotus (Janspeed) sport which I removed. It was very close to the shield behind the number plate, I gave it approx 2-3mm clearance but could easily have been contacting if I hadnt noticed. Sounds great.
After I fitted my 2bular GT3 I ate a Zing-er burger from KFC, it was very nice but I like the fillet ones better.
Also check the clearance to the diffuser, mine touches and makes that kinda zing sound if its not pushed over as far as poss when tightening.
If it is a light metallic buzz it is probably one of the heat shields behind the number plate plinth, the 8" rear box is a very tight fit 
In warmer weather mine can zing the same - it is heat shield or diffuser expanding and fouling something or other. Certainly not anything going on in the engine.
thanks guys, shes at the doctors this week having a few mods …i’ve added it to the list! its certainly not detonation. thanks again
mine had one at 2800, was the exhaust on a sheild
found out today its the 2bular exhaust. the standard bracket doesn’t fit, so wasn’t. Jim is in contact with lotus silverstone about a mod. think jims been unwell and a bit behind. they are waiting to hear from him. worst case they will fabricate a support clamp. job done.