There is a stage 3R kit:
STAGE 3R TURBO UPGRADE KIT
PT# P5007864 - with Turbo Toys - Stage 0 to full Stage 3R with Turbo Toys
PT# P4510338 - without Turbo Toys - Stage 0 to full Stage 3R without Turbo Toys
PT# P4510339 - Stage 2 to Stage 3R upgrade kit (Stage 2 w/toys = Stage 3R w/toys, Stage 2 w/o toys = Stage 3R w/o toys)
THESE ARE THE ONLY KITS BEING PRODUCED, THERE WILL BE NO OTHERS DUE TO EXCEEDING EXPECTATIONS OF ORIGINAL DESIGN!
Stage 3 Turbo Upgrade Kit Components
(1) Stage 3 PCM
(4) 682 cc/min Fuel Injectors*
(1) 3.0 bar MAP sensor*
(1) 3.0 bar TIP sensor*
(1) Block-off connector for PCM
(1) Mopar TD05HR Turbocharger Assembly (with integrated exhaust manifold) and Penta-flange Exhaust Elbow
(1) Demand-regulated Fuel Rail Assembly
(1) 180lph Fuel Pump Module
(1) Fuel Rail Regulator Hose Kit
(1) Exhaust Gasket
(1) Exhaust Flex Joint Gasket
(7) Exhaust Manifold Bolts
(6) Oil/Water Banjo Fitting Sealing Washers
(1) Oil Return Line Gasket
(1) Vacuum Harness Securing Kit
* items not included in the Stage 3R upgrade kit
P4510647 Performance Clutch
P4510548 Blow-off Valve Conversion
W Speed-rated Tires
P4510461 Cat-back Exhaust System
NGK #4306 Spark Plugs (or equivalent)
Spark Plug Gap of .035"-.040"
There is no longer stage 3, its all one stage 3R. I thought that I remembered that originally stage 3R would have super sized 7xx cc injectors, but I guess thats out.
The AGP kit is going to be substantially less expensive, I PRESUME. The guess is that the mopar kit will be anywhere between $2,500-$4,500. Best guess is around $3,500 for a complete kit. The AGP kit is around $1,700 which will get you to 300hp, add a fuel kit for $900 and you can be around 375-425hp, depending on your tuning capabilities.
The mopar kit put out 369hp to the wheels in the only known dyno run (feel free to correct me) in SCC mag. That car has also run an 11.83 @ 119 mph. Keep in mind though that car was lightened around 450lbs or so.
Bottom line: mopar puts out around 370 hp to the wheels without tuning. AGP HEAVLIY relies on your tuning to get the numbers, but has a huuuuuuuge upswing on peak #'s. Cost is in AGP's favor. AGP makes a quality kit, as almost everyone knows, and I would imagine that the mopar kit is just as professional.
That said, I'm gonna start saving up for the mopar, because my SRT-4 is a daily driver that I can't afford to spend weeks tuning. If it were my 2nd car then I would go AGP GT40. Either way you get a great kit. You can also look at PSI-FI, but that's another thread...