Found some interesting information on an American site about tuning the RX-8:

1. Intake – enlarging the oval inlet to the factory air box - +2 HP (this modification eliminates the VFAD intake duct.) Developmental work is still being undertaken.
2. Headers – approximately 4 HP peak power gain.
3. Mufflers – muffler & connecting pipe - 2-3 HP.
4. Removing the muffler from the car (engine) – about 4 HP.
5. Remove catalytic converter and resonator from the engine completely, and replacing with "cat" replacement tube – max benefit 8 HP – regardless of what muffler is used (or even no muffler).

https://www.racingbeat.com/ConRX8.htm

I've run the car without a muffler, and it's pretty damn loud.

 

So the end result is approx 2K for four eighths of two fifths of f**k all.......and a lot of noise. Sweet...!

 

I love this sort of info. The fact that there is little to be gained by these sort of tweaks shows to me that Mazda have thought hard about optimising performance.

 

Interesting. And it doesn't take much to get 2 dyno charts to vary by 8HP with the same config!

Cheers,
Hymee.

 

so maybe all that is needed is flywheel, maybe pullies and the most important ecu a/f and timing tuning? (besides pulling the motor out and porting)...

 

Just the pulleys would give you 5 to 10 hp, wouldn't they....?

 

I wouldn't say the pulleys alone would give that... maybe pulleys and flywheel together may give 10 hp but what they give is faster and better throttle response from less inertia

 

These guys claim 8rwhp.....Too dear though.

 

most companies are claiming ridiculous numbers
e.g air intake claims to be 8-12hp
exaust/midpipe up to 22hp gain
pulleys 8-12hp gain
(all have dyno's to 'proove')

hard to believe some of these extraordinary claims even with the dyno sheets...

 

On most cars the figures you mention are not ridiculous....The 8 is finely tuned already though....
Of the three, IMO the pulleys are the only one that would come close to liberating that amount of hp.

Gomez.

 

Loose 5 kg around my waist = 5hp gain!!

 

pulleys are kinda dangerous to use tho if not implemented correctly... dun wanna dmg nething around the engine

 

i'm a firm believer of weight reduction when it comes to the RX-8, strip out the seats and sound proofing and it's a battle wagon