Traxxion and RT have just about anything you need to beef the suspension up, but they cost a lot for what they deliver. Much of the kit they sell really does little to help.
Progressive gives best bang for the buck IMHO, front springs and rear shock from them will be ideal for most riders.
Zeke, have you ridden Traxxion and Race Tech bikes?
I don't understand your comment that the kit does little to help, and doesn 't deliver a lot of bang for the buck.
The Progressive shock is comparably priced to the Traxxion, although I don't see one listed on their website right now. The Race Tech is a bit more. I've had experience with the Traxxion shock, and it is a good performer. The stock shock wears out quickly (25K miles or so) and the spring is way to weak to hold up a 900 lb behemoth, let alone rider and passenger. If you are planning on replacing the spring, find a new trike take-off and do the shock too.
If you are doing fork springs and a fork rebuild, you will see a goodly improvement. If you going that far, either monotubes or better yet a Race Tech Gold Valve kit will give you a lot of bang for a reasonable investment.
Then we get to the holy grail of suspension upgrades. Traxxion is often sold as a kit, for a number of reasons. It's easier to do it all at once, rather than keep taking it apart. You are in the shop once, not again and again. That doesn't mean you can't pick and choose what you want.
Each part improves a specific deficiency in the GW suspension.
The All Balls roller bearings take care of the dreaded decel wobble.
The AK20 cartridge kit totally replaces the guts of your forks, giving you a modern cartridge type suspension, springs of a proper weight for your weight and riding style, new fork caps to give you rebound adjustment, and the right weight fork oil. The improvement is dramatic enough that you notice it before you get out of the driveway or installers lot.
The fork brace improves low speed handling by stiffening up the steering, making it more responsive.
If you opt for the Mega Monty, you also get a new triple tree and bridge, which further stiffens up the steering and make it much more precise amd responsive.
The shock takes care of the back, both damping and spring rate, and also gets your preload adjustor working properly
Any or all of these upgrades will give you both better handling, and more important, a better smoother more compliant ride. (Well, OK.. the fork brace and tree don't really contribute to ride quality..)
As Paul Thede from Race Tech says, the best you know is the best you've ridden.