I have two TC3s that are fully decked out in IRS gear. It is over priced....but I work in a LHS and the employee discount helps
The chassis has different "flex" properties than the AE graphite one. It keeps the car glued to the track and the car does exactly what you want it to do. The car kinda "springs" out of the corners and is very responsive. Because of its stiffness it can take turns very well, and accelerates out of them quickly because of the lightweigt (very good for stock racing) If I tell my car to do something, it does it without any loss in traction. My car has Futaba standard servo in it, and the few people at the track I let drive it swear that I have a high speed high torque servo in there (I had to show some of them that it wasn't). If you do get the chassis kit, I will also recommend getting the graphite stiffining kit. This replaces the corner braces with carbon fiber ones, and has two more braces that run down each side of the car. This stiffens the chassis even more, and keeps all 4 tires on the ground where they belong. Before I got the chassis and stiffining kit, If I got in trouble and turned into the turn too early and had to steer the opposite way to correct, my car would break loose and lose all traction and hit the boards. Not so with the chassis and stiffing kit, the car does what I want and I can save myself in the turn and get through it safely. When I drive the car I let off the gas going into the turn, full steer right or left, give it full gas, and the car shoots around the turn with no problems.
Other notable IRS stuff:
Input shafts: A MUST! these are much lighter than the stock steel ones and reduce rotating mass to improve acceleratoin. great for stock racing.
Aluminum outdrives: I think they work good. Lightweight, less rotating mass. But others think that the plastic ones by AE are the best (see recent flame war in TC3 forum). Only problem is that they wear quickly.
Driveshaft: Eye candy. No performance increase or decrease. It is heavy and some say that it will slow your acceleration because of rotating mass. I ran my car with the aluminum one, and then with the stock shaft and campared lap times.....they were the same.
Drive cups: Eye candy. Same as driveshaft. I have seen the plastic ones break though and aluminum will hold up better. Looks great with the drive shaft.
Spur gear adapter: Doesn't warp like the plastic ones sometimes do. If you use this make sure to locktight the spur gear screws in it or they will back out. You may have to put some shims between it and the Big E-clip to reduce play.
Battery strap: eye candy. Dissapates no heat at all, I'm not sure where they got that idea from. Looks great with the driveshaft. I had a problem with my batteries slidding out of the car with this strap. I fixed it by putting a O-ring under the body pin and then tightened it down by turning the pin. Problem solved.
Servo/Transponder mount: Not too sure the purpose behind this one....I was told that it reduces steering slop.
I talked to Dave Irrgang and he said that the chassis was designed for carpet racing. I race on low bite asphalt and it work great. I will post pics later on today (I'm at school right now, d'oh). Hope this helps you out
. PM or email me if you have any questions.