So I finally finished up with the rear floor and fire wall on the XP5 and feel that I really made a good improvement on the engine noise! So here’s what I used, First. Killmat and Rezonix pro CLD squares first layer, Second. I replaced the felt liner and installed RezoNix lead sound barrier cut to size of the felt liner and bolted to the fire wall like the felt liner was. Third. Cut RezoNix fiber mat 45 to the size of felt liner but just straight across at the bottom and install over the sound barrier. Installed upper back set (it was a tight fit). Installed some more RezoNix pro CLD squares on parts of the lower sections back area walls and installed lower half of the seat. Installed Dynadeck on the rear floor.
The wife and I jumped in went out for the test. Didn’t take us long at all both of us said that’s definitely an improvement! I didn’t have any prior measurements but I used my phone for a db reading and saw 78 to 80 db at WOT approximately 8100 rpms (Not sure on accuracy on phone app?) WOW I said that pretty damn good lol… So we both think that it was definitely an improvement over just the kilmat and the factory felt liner by far. I believe I can live with the noise levels now easily.

I really think that the lead sound barrier and the fiber mat 45 really provided the biggest difference! Really would love to see what the db levels would be using the sound barrier all over the back wall? But you would probably run into a fitment problem at some point.