I am biased. I have ran LRD/LED for many years. I can't testify to making just a pipe swap on a TRX. I have ran his engines and pipes. Always smiles.
Before I had started using Arlan I had Streamline racing do a mild build on my banshee. Ran it for a while and liked the bike. It was running old school FMF woods pipes. I swapped over to some LRD adjustables and they did make a noticable difference. Even shortened up they made more bottom and mid. Still felt the same on top.
At that time I was riding sand, but was hitting mostly sand trails.