three inch exhaust

In my opinion, the manufacturer would gladly leave the heat shields off if the standard exhaust didn't cause a potential problem. I'm pretty sure that a non-standard exhaust that is closer to the parts that are shielded will cause a problem much more quickly.

Remove them if you don't mind catching fire when you least expect it.

Mate; are you talking about the heat shield/s on the exhaust manifold or the one under the floor pan, just above the muffler?
Mine has a 3" system with only a small hotdog muffler. The original heat shields are still in place and I can't imagine any advantage in removing them.
Cheers
Roachie

Yep, please be more specific.....model car for a start....id have to say that there will be no problem associated with the removed heat shields...they will be quite happy to be removed and out of harms way:-)
Andrew

We had a 3inch system fitted to our 4.2T and we replaced the heat shield around the manafold ourselves. The exhuast system certainly improved the performance of the car.
Cheers
Jenkie

When I changed my GU 4.2 TD exhaust to 3", the heat sheilds where removed and I had the section that goes under the cab High Performance coated, keeps the heat in and not into the cab, works well.

I left the heat shield off the piping for my MTQ 3" system. Partly as it was a bugger to put back on but mainly as it was causing premature corrosion (rust) on the original exhaust after only 35,000k. I thought this was a much bigger issue for problems later on.

The shield on the dump pipe and turbo was put back on with the holes moved a tad. The mounting holes pentrate into the exhaust flow so the bolt must go back in at the very least.

Have had no issues with heat at all but it is a little noisier but still no problem. The Original heat shields were packed with an 'asbestos' looking material that trapped the water and I think that Nissan's maini aim was to reduce noise rather than heat. This stuff trapped water and hence the rust.

I'll post if I have any problem with it setup like it is.

cheers
JamieMac