[svxistentialist]

The heat shields are there for a reason.

No doubt many have taken them off because of the buzzing or rattling, or changed to a system that did not use shields. The -ive effects will be long term, mostly.

More radiated heat will get to the floor of the car, which will then heat up the interior. In summer, this will give your aircon much more to do.

A possible worse effect is long-term, this extra heat may harden and perish any wiring harnesses around the transmission tunnel, and possibly any other rubber parts in there.

Long term, as I say, problems from this would not show up for a while.

You pays your money and takes your choice.

Joe