I've never tried one. Most of the ones I have seen are just too big and look ridiculous at address. I'm more interested in accuracy anyway. Golf is not a distance contest.

    Balleszabal All those posts of players in other forums claiming they are gaining 30 and 40 yards ,IMO,is pure fantasy.

    I recall that someone on the Wishon forum put it this way....and Tom said that was pretty close..... going from a legal .830 COR to a .870 COR (which was the 959OL) was about a 5% COR increase. So, if you hit a 250 yard drive normal, you might get 262.5 yds with the non-conforming COR.

    That was pretty much what I saw when I had a 959OL.

        I only play recreational golf, mostly as single , against the course. I WAS looking for for a few more yd so I could keep playing from members tees and still have some greens in regulation. Read about higher COR heads, shaving, etc and came across a non conforming 0.86 COR MAX face TM quad. At Pkay it Again store in Apex NC for $35 so gave it a try. Never saw any real gain in distance. My old Ping G15 stayed in the bag. To be fair , It was also smaller size less forgiving of missed center contact, wrong loft 10.5*, for sub 90 mph swing, and stiff tip flex shaft. I kindof wish I'd experimented more with cutting down the shaft and making it like a big thriver like club as it hit pretty well off the turf and teed low. Felon balls another experiment that didn't go anywhere significant much either but was fun .
        I moved up to senior tees, happier GIRs now, and on days when I feel lucky , still drive from an occasional shorter members tee box. If I want to see nice long hits, just watch Lexi.

        This was a long time ago, I don't recall any details. Maybe I am not remembering correctly. So I would not speculate and make myself sound more stupid than I already are.

        Balleszabal Well then, you are finding out just what I said to be true. Publicized lies by the companies that made those heads you have.

        You cannot hit them any farther than others.
        The USGA does not publicize the reason the heads(on the list) are non-conforming; the selling company puts out that statement!
        Some of those heads may not even be on the list due to the company not sending them in and wanting to make sales of(self claimed) "non-conforming"/ "illegal/hot faced" heads.

          BTW
          What length is the 919? I'm experimenting with shaft length now trying to optimize distance vs dispersion. Not sure Wishon doesn't suggest too short lengths for us old slow swinging guys

            Provisional
            I have a slow swing speed, and experimented with various length driver shafts. Found that at 43 and 43.5 I would over-swing and lose hitting the driver face in the center. When I made good contact, it was noticeably shorter. Found that 44 or 44.5 I make good contact , swing more within myself and my distance is as good as it gets.

                There have been component companies that advertised their head as "hot" when it was never tested/ruled such.

                Bigborgel
                I cut down the new shaft for my old G15 head to 45.0 from old one 45 3/4". We're working at being friends... I grip down usually so effectively I am playing it < 44.5". So far it goes either low draw /pull or straight where it's aimed. Having to adjust to find ways to work it to give right spin.

                  I read somewhere that older driver faces change COR because of being impacted upon so many times, increasing in delection & rebound from metal fatigue.
                  I have no idea if true but also don't know if PGA ever appropriates winners drivers to check if > max allowed; doubtful. Once model gets approval you can play it with no further test, I think. In motor sports, motor tear down for big winners to assure legality compliance was pretty standard I think.
                  Maybe some one here has actual knowledge of facts about it.

                  Back to the original post.
                  If you want non-conforming = distance, buy a golf ball that gives you a benefit on something other than a driver.

                  Regarding yardage, I do believe it is "possible" to achieve big yardage gains if you stumble across the right head with the ideal specs, matched with the right shaft and the right golf ball.

                  As yardage goes, I have no clue what my average drive is.

                  I have played with people who say "wow! That drive was XXXXXX forgetting you have to take into account where the tee markers to determine the length of the hole on the scorecard are vs, the set up for that day, where the ball landed (down slope helps, wind) etc.

                  That is 14 shots out of xx. But what how did you score?

                  If I need yardage as I get older, I'm moving to more forward tees.

                  Yes, the Wishon 919 remains a serious contender. With the correct loft and shaft it MIGHT give you those extra yards, but regardless, you will probably be in the short grass and the sound and feel are great.

                  The 919 is in my bag and I'm debating one last try at adjust-ability / newer technology, or simply trying a different loft as I have changed my ball position on tee shots.

                  Cheers to TW.

                  The ratio increase in ball speed vs a max legal COR is simply (1+New COR)/1.83. Swing speed has nothing to do with this ratio. So if you can find a .9 COR driver then your ball speed will increase by 3.8%. All else being equal your carry distance is pretty much directional proportional to ball speed for your particular swing.

                  If you can carry the ball 250 yards you pick up 9.5 yards, hardly earth shattering. Lower carry distances increase by a proportional amount i.e. a 200 yard carry increases by 7.6 yards.

                  Apparently a .9 COR is the outer bound of possible COR in a functional clubhead. In reality most if not all non conforming for COR heads are lower then .9.

                    I own a DTG Felon driver and have hit it many times. I also used to own a Integra driver that was supposed to be non-conforming. I can't say that either one gains me much in the way of maximum distance. I'm sure it's not more than 7-8 yards. Most of the time I don't get anymore yardage than I can get with my best drive with a conforming driver. What I can say is that I get my maximum distance more often with the non-conforming Felon than I do with the conforming one(s). They're fun to goof around with but kind of a waste of time because you could be grooving a better swing with your legal driver instead of the illegal ones while you use them.