Rattle sound going in-between 3.5 k and 4k RPM

Hello fellow Jimmy owners, I have noticed a weird rattly noise when I accelerate to about 3500 and 4000 rpm, any rpm's above that or below, is whisper quiet. If I rev from a standstill, I don't hear anything but if I am on road and I rev upto that dreaded point, I can hear the rattle.

I took my car to two mechanics who either couldn't notice the sound or they just told me to change gears and that I am reving out.

I took it to an exhaust shop and the person said they was nothing wrong.

Finally, I took it to an official Suzuki dealer where they said it was the catalytic convertor. But its suspect because there's no check engine light and the car turns over and drives smoothly.

I have tried to change the air filter and spark plugs but that didn't help much.

Has anyone experienced this?, What are other alternatives to getting a new catalytic converter.



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Could be the heat shield attached to underside of car
heat shield on the cat itself 
new cats on e bay for around £70

As Jack says it's probably a hear shield, is it a zingy metallic noise?

Its already been said above, but just to be clear it's possible it's the heat shield that is around the catalytic converter, on the exhaust, not on the car body. They rust / fatigue at the weld joint, it's common for it to look fine but close inspection will reveal a crack or snap in the front pipe.
You can weld it back, but you are just extending the inevitable - a new catalytic converter.

That is how mine failed and funny enough it had a rev dependant rattle just like yours.

Get underneath with the engine running and have a feel for escaping exhaust gas around the Converter, a sure sign it's broken. Careful not to burn yourself.
Catalytic converters are cheap enough and aftermarket work fine on the Jimmy.

Yes, it's a metallic rattly noise

Then get an assistant to hold the revs in the range that makes the noise and get under the car with a sturdy stick and applying moderate pressure check around the exhaust and its immediate path touching every bit you can and isolate what is making the noise. Be aware that catalytic converter will run at upwards of 600 degrees Celsius so don't touch with anything you don't want to burn.