Stiffens up the ride a little. No more than expected. Took 2 hours to swap both sides by myself. Only tools needed were a floor jack, a piece of wood, 18mm socket, wrench, and some silicone grease.Be careful lifting the body in respect to the front bumper. Don't want to lift any more than necessary. *edit 3/12/19*Road vibration increased. Massively. The factory bushings were swapped at 200k after a complete replacement of the front/rear suspensions. All parts were GM Original equipment with exceptions to Cognito UCA's, Kryptonite tierods, PISK, and hubs, RareParts Idler/extreme pitman, SuperSteer Idler bracket, Redhead steering gear, Sway-A-Way Torsion bars, Spohn adjustable rear upper, lower ca's and track bar, Bilstein 5160's,... you get the idea. Swapped bushings with no issues, road fine for a few months. Then the vibrations started. To be clear, Poly bushings are stiffer and will increase vibration transfer between the frame and body. Period. I was expecting and fine with this. First thing is that the poly bushings are not as thick as the factory rubber bushings. Some say this is because the rubber will settle to the average thickness that the poly are manufactured to, while the poly will keep its original shape. After years and miles of wear and tear, the factory bushings will conform to the wear and settling of the body in relation to its configuration on the frame. This equates to bushings settling at different thicknesses across the frame/body mounts. When you drop in poly's, some will be thicker, thinner, and equal to the settled rubber. Yes you can tighten them down to mitigate the differences but it is an exercise in futility. After 12k and constant checking and adjusting, there are still bushings that are up to 1/8" too short to fully engage their position. This has resulted in frame harmonics or "beaming" and clunking at certain speeds and/or terrain conditions. (clunking not associated to intermediate steering shaft(s) or bearing, all replaced) Original factory "cushions", as they are technically referred to, run about $100 per set and you have to track down the upper, lower cusions, bolts, spacers, everything separately. On a '03 z71 Tahoe that's $800-$1000 for parts only for the whole package including the radiator support bushings. Aftermarket runs about half that.After replacing the poly bushings back to rubber, all issues have disappeared. Had an annoying height difference between my rear tires of 5/16" that is now equal. No more vibration at any speed.No more clunking. No harsh road transfer to body from frame.And the end all to drive the point home, my tire/fender clearance has settled to a 1/4" increase over the poly bushings, eliminating all rub and allowing me to run the full 33/12.50/17 tires like it use to... and that's a lot when you start cranking torsion bars. With all the performance parts installed that 1/4" allowed me to drop the front enough to be in the upper tolerance of my "Z" measurement, thus placing my lower ball joints within acceptable range and massively reducing their wear and also allowing for almost perfect steer ahead in my alignment and no bump steer. Over all I have to say the poly bushings are good quality and will perform as marketed. But the decay rate on modern rubber bushings is almost equal to poly over severely long periods of time. I've had poly bushings on another vehicle for about 7 years and 110k and they are worn as much as the factory cushions I pulled off my Tahoe. It all comes down to budgets and preferences.