I have the Leo Vince on my 2021 MT09 and it does NOT weigh 16 lbs, not even close! I weighed it on my digital scale and it was just under 11 lbs (weighed with the DB Killer removed and without carbon fiber cover, but with all necessary fasteners and springs).
I was going to start a new thread, but since the LV has recently been discussed and recommended here, I'll mention the "mods" that I had to do in order to properly fit the LV onto my bike.
I have no mods to my bike that would affect an exhaust install, but no matter how much I jiggled, wiggled, pulled and pushed, for some reason I could not get the RH header pipe to snug up, even before tightening down the header flanges and bushings. I was left with about 4mm of up-and-down play and the only way I could remedy this was to buy an extra exhaust gasket from the dealer and double up on that one RH side. It worked but I didn't like the fact that it reduced the amount of threads that the flange nuts covered, since it effectively pushed out the flange about the thickness of the extra gasket.
So...I reached out to a machinist buddy from my other vintage Kawasaki Triples forum and he machined a 4mm thick "ring" that matched the LV bushing's INSIDE measurements and he tacked welded this right up against the original "step" that the header pipe butts up against. So basically it pushes the header pipe out and down into the collector by 4mm and seals perfectly like it should have to begin with.
I don't know why I had this slack in this one header pipe, and others may not run into this same issue - maybe it's just my particular bike (slightly off tolerances perhaps)? Or maybe I overlooked something during install, but there's only so much involved in this exhaust installation. Not a big deal to me really - it sealed up just fine in the end and it only cost me a few bucks and about a week+ downtime while he machined the "ring", plus the shipping time.
The other minor adjustment I elected to do - and again, your bike may not need this, is I didn't like how close the exhaust tip was to my swingarm using the included steel spacer. So I picked up these 3 different length spacers and simply selected three that suited my clearance preference. I took some pictures but like the exhaust weight pics, I don't know where they went...
https://www.amazon.com/dp/B08M6B7MKH?psc=1&ref=ppx_yo2ov_dt_b_product_details
I'll repeat a third time that in all likelihood you probably won't have these two issues, but if you do, these are my remedies. I never considered giving up on the Leo Vince and going with a different exhaust system because this exhaust is BEAUTIFUL and tucks in so nicely under the bike just like the OEM system! And even though in my case I had to spend a few extra dollars for a couple of "adjustments", I strongly feel that it was and is worth the effort! The Leo Vince is also quite a bit less expensive that most other exhaust systems, so in the end I'm happy with the results, and would recommend this system on the MT's.