What is there to gain

I have a Vpi HW19jr TT w/AQ PT6 tonearm. I see a ad for a heavyweight counterweight. What would be the sonic benefits to using this counterweight over the stock weight?
Scott, let's put it this way, OH MY GOD!!!!!!!

EVERY aspect of your tonearm will improve. Tonal quality, compliance, everything....... will improve.

I just installed the Expressimo end stub and the Heavyweight counterweight on my VPI MkIV/Rega RB900. The difference was absolutely PROFOUND. I'm not talking about subtle differences, they are immediately apparent from the first 30 seconds of playback.

Scott, don't even hesitate on this one. You will be Soooo satisfied with the results. Worth every penny you will spend and then some.

I am positive you will receive other praise from other users in this thread.

Happy Listening, Ed.
my setup,same as yours, must have came with an aftermarket heavy weight. mounting a benz gold, had to add a strip of lead to weight the head, as the weight was as far forward as would go.
would suggest the mark III plater/bearing for a big jump in sound.
if you go with the hvywt i'd be interested in your stock PT-6 weight. kurt

One of the benefits is that you would continue to feed your habit. Nothing like the path of least resistance.
About two years ago, I started a thread here after I installed the Heavyweight Counterweight on my Rega RB-900 (with VPI HW-19 Mk 4 turntable), and my commments were basically the same as Buscis2's. I have been an audiophile for about 40 years, and have not been much impressed with most of the "tweaks" I've tried or read about. The Heavyweight Counterweight, however, is worth every cent, and makes a MAJOR difference in the performance of my RB-900 arm. In some respects, the money spent on the Counterweight may well be the best "return on investment" I've ever heard with my analog front end. I've only given an unequivocal recommendation to a few "tweaks" over the years, but this one is probably the only one I've had no hesitancy about it.

If you want to review my original post, here is the link to the archived thread:

And, for what it's worth, the last issue of The Absolute Sound reviewed a bunch of after-market products for tonearms and turntables, and the reviewer gave what was essentially a rave review of the Heavyweight Counterweight.
I am going to try and build one of these. I will let you know how it turns out.