I'm not sold on the Nitrous systems. Yes they do make quick power but, man, I just can't bring myself to put this on the 8. I'ts good for straight line acceleration but not a good application for road racing.

I agree. While it would make the car fast from a stoplight perspective I personally prefer upgrades that do one of two things. Improve the reliabilty of the car or improve the road racing style performance.
such as:
-improved braking
-improved cornering (higher skidpad g loading)
-improved overall handling (higher slalom speeds)
-Improved acceleration across the entire rev band (while nitrous does this It doesn't seem like something you can use coming out of a double apex or through a set of switchbacks and still control the car)

I've read articles on the FD's where replacing the pre-cat downpipe with a smooth larger diameter pipe improved the overall flow of the exhaust and also helped reduce the engine bay heat problems. Does anyone have any input as to whether this is beneficial to look at for the 8?

Well on the 8 there is no down pipe. Be fore the cat is only the header. Putting a better header on will increase the flow but H/P gains will be minimal untill engine management is used.

I see...I've been reading the threads on header design and that sounds pretty complex with the siamesed ports.

PCM tuning seems to be a common thread (no pun intended). It sounds like this is the first bottleneck in the system and the best place to spend your money first for perfomance gains.

I agree with this entirely. If we can retune the car to get us 20+ more horsepower at the wheels using the stock intake, exhaust, etc, how are they hurting power very bad? I'm not saying you can't get more power out of an intake and an exhaust than stock. You'll just get much more power everywhere for the money by starting with the ecu first.

The only problem I see with the ECU (at this point in time) is what we have just see with the "L" flash... Mazda switched up the fuel maps on us. And in turn ECU piggbacks have to be reprogrammed. If it was as easy as windows/Red Hat/Gentoo to update to the latest patches... then I'd say no problem. But having to pull the unit out of your car and send it in... that sucks. What sucks even worse is if you buy the Greddy kit or other turbo managed by eManage.. then Mazda changes fuel maps and timing, so now you have to reprogram the unit or take it to the shop to be returned.

I agree with that. That is definitely a problem with some of the alternatives out there right now. I don't think this would be an issue with Ric Shaw's ecu though as it is fully programmable. A new map would just have to be programmed in on the laptop. There will be others later that will override the stock ecu. We'll just have to wait for those.

The latest version of Canzoomer's ECU (includes a USB port) can be upgraded by the end user if they buy the reflash kit (cable and software). It is also possible to make any adjustments you want using a laptop if you buy the programming kit (cable and tuning software).

To piggyback on what Speed Racer has to say, CanZoomer will make new maps available for download to people who buy the reflash kit. This USB kit is $75 USD as I recall. $50 more will get you the full programming kit, which allows you to do CanZoomer's new maps AND tweak the settings yourself. Heckuva deal, considering Mazda seems to be releasing a PCM reflash once a month or so right now. No other tuner that I know of besides CanZoomer does anything like this.

That is a good feature.

Well that does address that problem for most people...

Another new guy thought popped into my head for power gains.

I know people have talked about porting the engines and expressed concern over how to open up the siameesed ports on the renesis or how much room there is to open them. How much would be significant? Has anyone tried extrusion honing with a polymer abrasive paste? This would open up the ports a thousanth or 2 on a side and maintain the same shape...maybe radius the corners a little. Does anyone have any experience with this?

There would actually be very little point to that on the exhaust ports of the Renesis. There are exhaust sleeve inserts in the engine housings which the gasses flow through. These are held in with 4 cotter pins. The center siamesed port can be dealt with in 2 different ways. One is to just build a special header that accounts for this in it's tuning. The other is to completely machine a new sleeve with 2 seperate flow paths, then construct a proper header. I suppose some grinding could be done to the stock sleeve. I'm sure the inside radius edge is quite sharp and could benefit from a more gentle radius. The outer exhaust ports have a sufficiently large runner to flow the necessary gasses. The center port only flows about a quarter of what the outer ports do. It is ironic that this is the port runner on the exhaust that is the key to tuning.

i wont deny it im new at cars but i got this rx8 so for the past 2 months i have learned sum things about cars but what r headers

As for the B&B Exhaust there are also race pipes that you could install.. what are the race pipes, arent they like downpipes?

The B&B race or "test" pipe is a catless mid pipe with a resonator that removes the factory cat for track or high performance applications.

So, what do we have?
 

JDM Original RX8 247HP at the crank (Assume 20% loss on a Drum Dyno = 197 RWHP)
USDM RX8 238HP at the crank (Assume 20% loss on a Drum Dyno = 190 RWHP)
RX8Club Member RX8's make 210-225 HP at the crank (Assume 20% loss on a Drum Dyno = 168-180 RWHP)

Intake +2-5 RWHP
Header -1 to +5 RWHP
Street Legal Mid Pipe/CAT +5-8 RWHP
Offroad Race Mide Pipe +8-9 RWHP
CAT Back Exhaust +3-4 RWHP
Flywheel +2-8 RWHP*
Under Drive Pulleys +2-10 RWHP**
Grounding Wires +0-1 RWHP
Street Porting +10-15-?? RWHP
Piggy Back ECU +10-20 RWHP
Stand Alone ECU +20-25 RWHP
Turbocharger +50-60 RWHP (GReddy Dynoed @ 240 RWHP with E-Manage and 291 RWHP with Interceptor-X)
Supercharger +30-50 RWHP
Nitrous +50-75 RWHP

*The flywheel HP gain varies from gear to gear. It is very prominent in the lower gears, not a large gain in the upper gears.
**Underdrive Pulleys may not make this gain either. Some have had success, while others have not. Gains come at the upper RPM band.

IF you low ball the whp at 180(i tend to believe it is really 190) and add the roughly 40whp you have in your list we are at 220 with no fi which i think brings us back to the original spec. i would like to see how much T those on your list add and where in the rpm range it is.

How much naturally aspirated hp can one get out of this motor?

well the original rx-evolve concept was rated at 280ps crank which was probably close to the max NA hp limit. but that was with a higher rev limit. maybe 300ps crank? no one really knows outside of Mazda.