I think Dave @ Powderlites makes the best stuff available for guys today. The kits are extremely well thought out systems, and they work very well. Assuming this is for a Nytro? You get a ceramic coated header & turbine, divorced double downpipe, large IC that flows properly, RB3 controller that gives you full control over fuel & timing (with built in stutter). You get a head shim and a cam timing jig and it comes with an A/F gauge. If you're planning on running big boost they even make their own connecting rods now. There is a section on this forum dedicated to fuel/timing maps that you can share with other owners, and the quality of his kits are second to none.
The guy that designed and built your kit is either going to answer the phone himself if you call, or be standing 10' away from the guy that does. Powderlites has the best customer service in the business. Then there are guys like Dave (Hurricane Racing) and Cliff Yeatman that are constantly tweaking to make a great kit even better. You won't find better support for a kit. All of these guys post here regularly, and there are many more knowledgeable forum members that can share some wisdom with you.
That may sound a bit one-sided (and I'm sure Impulse makes good stuff), but if I was looking for a new kit today the choice for me is really a no-brainer.