Freelander 1 ENGINE UNDERTRAY & WHEEL ARCH LINERS - BIN?

My buddy and I are both getting our Freelander TD4 2004's undersealed next week. Engine undertrays and all wheel arch liners will be coming out. Is it worth putting them back? I've checked the forum and some say the liners can be mud traps or simply hide rust, better to see/fix it. But apparently the liners deaden road noise quite a bit. Some owners just reluctant to throw away bits of the car's original equipment. On mine, a previous owner cut a hole in the undertray to expose the sump plug. Neither car is used off road or modified.
What's the feeling - keep or bin?

Keep the liners in place, but use waxoil behind them, before putting them back on.
If you don't put the liners back, rust will form in no time.

The sump guard also keeps the muck out the bottom of the engine bay.

I don't see the point to not put them back. They are there for a reason and relatively easy to take off if needed.

Clean out the threads and nut for the undertray with a tap/die, makes a lot easier to put on and remove again.

Hi guys and thanks very much for your advice. As a result I will be keeping both undertray and arch liners. Do the mud flaps and black plastic arch extensions need to come off for the underseal to get at all the metal? And if the liners have never been off before, will any of the fixings give trouble?
There are what look like roofing bolts holding on the mudflaps with very rusty heads (see photo) - can these give problems?[GALLERY=][/GALLERY]

On closer inspection those "roofing bolts" are just plastic rivets with now rusty metal washers behind them. Just in case, I've bought a kit of replacement plastic arch clips (various sizes) on eBay - only cost a few quid and saves much grief if clips break. And thanks for the tip regards running a tap through the undertray captive nuts.

Put stainless bolts in too. Easy to remove forever!!