The earlier models of the RX-8, having chassis codes SE3P, and JM1FE, were produced from the 2003 model year, though the car's U.S. debut was for the 2004 model year. It is powered by the RENESIS 13B-MSP (2-rotor, multi-side-port) Wankel engine displacing 1.3 L (1,308 cc). The 4-port standard RENESIS was rated at 191 hp (194 PS; 142 kW) and was coupled with either a 5-speed manual or 4-speed automatic transmission. The 6-port high power RENESIS was only available with a six-speed manual transmission and was rated at 238 hp (241 PS; 177 kW). For the North American market, Mazda revised the reported output rating of the standard and high power RENESIS soon after launch to 189 hp (141 kW) and 237 hp (177 kW), respectively.[8] With exhaust ports now located in the side housing, the RENESIS boasted improved fuel efficiency and emissions rating over the 13B-REW employed by the preceding RX-7, thereby making it possible to be sold in North America.

At launch, the RX-8 was available in various models in different markets around the world. The variations according to different markets are as follows:

6-speed manual with a claimed output of 232 hp (235 PS; 173 kW) at 8,250 rpm and 159 lb⋅ft (216 N⋅m) of torque at 5,500 rpm with a 9,000 rpm (redline limited) (Sold in North America). This model was equivalent to the "Type S" trim in Japan.
5-speed manual with engine tuned to 189 hp (192 PS; 141 kW) with the redline reduced to 7,500 rpm. This powertrain combination was not available in North America.
6-speed automatic with manual paddle shifting option (introduced in the U.S. for the 2006 model year, replacing the 4-speed automatic transmission of 2004–2005) with the engine rated at 212 hp (215 PS; 158 kW) and 159 lb⋅ft (216 N⋅m) of torque with a redline at 7,500 rpm.This was the revised standard RENESIS, now with two extra intake ports like the high power version. The 2006 automatic RX-8 model also was given a second oil cooler, as was standard in the manual transmission model.
Automatic versions all had lower output/lower rpm engines due to the lack of availability of a transmission that would be able to reliably cope with the engine's high rpm limits.

Mazdaspeed:

In 2003 Mazda announced a factory Mazdaspeed Version of the RX-8 exclusively in Japan. Based on the Type S and tuned by Mazda's in-house division Mazdaspeed, the car included both mechanical, suspension, and aerodynamic improvements over the standard RX-8's. Mazdaspeed RX-8's were considered the highest performance model of the pre-facelift RX-8. Mechanical and suspension improvements included a new performance exhaust system, upgraded spark plugs, grounding kit, lightweight flywheel, re-balanced eccentric shaft, performance brake pads, stiffer anti roll bars, four point front strut tower brace, rear strut tower brace, as well as a set of height and damping force adjustable coil-overs. Mazdaspeed also redesigned the aerodynamics of the car, giving it a new front bumper, with enlarged venting and oil cooler ducting, as well as side skirts, rear under spoiler, and a rear wing. The Mazdaspeed RX-8 was offered in either Strato Blue Mica, or Sunlight Silver Metallic as exclusive colors. A total of 480 factory Mazdaspeed Version RX-8's were built, and had a suggested retail price of JP¥3,650,000.00. Mazda also sold Mazdaspeed accessories worldwide through their dealerships. These accessories included both parts that weren't equipped on factory Mazdaspeed RX-8's as well as nearly all the parts equipped on the factory Mazdaspeed Version. This allowed standard RX-8's to be upgraded to Mazdaspeed standards through dealerships around the world.