How much does the stock exhaust weigh compared to each (more or less) and what are the real whp/torque increases for each? For the money i think these two are the best sounding. If anyone has either let me know ur experiences with them.

 

When I weighed the OEM vs the Greddy the Greddy was about 2-3 lbs lighter. NO exhaust provides noticeable power gains, aftermarket CAT BACKS are for looks & sound. between the two I think the Greddy looked better, I have not heard a Borla.

 

I have to go the opposite way, (just to make things a bit more difficult for you)
I have the Borla Catback and absolutely LOVES IT! My butt-dyno tells me there´s a little increase in power (and that´s the dyno that counts when you´re driving, right?). And the sound is spot on Borla/Rotary-engine.... It´s very quiet unless you hit the pedal, and that´s the way I like it.

 

I have to agree w/expo in that there is no noticable change in power. I have the Greddy and bought it for the sound, not the hp. I love the Borla though, and would probably recommend the Borla sound over my Greddy.

Whatever you choose, enjoy the new rumble.

 

If you want loud and a much better horsepower gain for your money...you should go with a midpipe or the Rotary Performance Hi Flow cat.

Before you cough up ~$650 for an exhaust system you should read this from racing beat: WWW.RACINGBEAT.COM :

The following table lists the measured power gains from various aftermarket components. Testing has been conducted on the Racing Beat engine dyno with both pre-production and production Renesis engines.

1. Intake – enlarging the oval inlet to the factory air box - +2 HP (this modification eliminates the VFAD intake duct.).
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).

"The muffler "off" will yield about 4 HP, with a very loud exhaust note. With it "off" the car, the noise is unbelievable! We find 2-3 HP peak RPM maximum improvement from our exhaust, or any competitive system that we have tested. So someone can see from these numbers, it is quite difficult to get a lot more HP from this engine. The max potential with a header and race exhaust would be around 10HP."
Follow-up Notes

During the prototyping of our RX-8 exhaust, we kept hearing claims of rather large HP gains from other aftermarket exhaust systems. Since we were not observing gains anywhere near some of these claims, we decided to obtain two of these systems for our own reference. One of the systems performed as expected and produced around 3 HP, as did the RB prototype unit. However, the other system did not fare as well and actually produced less power than stock!

Since it is our policy not to "bash" or downplay competitors products, nor do wish to embroil ourselves in a controversy over HP claims, we will keep the brand names of these other systems confidential. Aftermarket manufacturers test products using various methods, and as you can see the results can vary!

It has been our recent experience with normally-aspirated Mazda applications that significant HP gains from an aftermarket exhaust system are hard to obtain. Mazda is simply doing a very good job with their exhaust systems! In today's horsepower hungry marketplace, it is unlikely that a significant amount of horsepower would be left behind in an ineffective OEM exhaust design. But hey, that's just our opinion! END OF RACING BEAT

So I would suggest spending ~300.00 for an ~8HP (midpipe or RP Hi-Flow Cat) gain instead of spending ~ $650.00 for maybe 3.5 to -1.5 HP gain....you might be the lucky one to buy the brand that will reduce your HP for ~600.00.

 

i love my greddy... but i have a HF cat too so idk how greddy alone sounds....

 

For me its really just a low price, good sound, and if im lucky, a small power increase.

 

Ive got the borla.....Im really happy with it...I like the sound..it gives it a more throaty sound....its deeper....and I like that...as far as hp gains....I know there isnt much....all I can say is that it feels just a little bit faster....Im not changing the midpipe or cat unless I decide later on to put in a turbo......the borla is the same design as the OEM so its an easy fit Im told..
Shinks

 

im looking around too and im pretty sure im leaning torwards the greddy

 

Wish I could hear the Greddy I had one before on a V6 and it sounded unbelievable.I have the Borla on the 8 and this Borla sounds awesome, I love it. Who cares about HP gains, the sound is worth a grand$

 

I have the GReddy SE coming in a week or two... look on youtube for a before and after video of the exhaust when I get it.... username Jea629

 

i love my greddy too just the right sound for me ... i think borla is deeper

 

you guys do know this thread is 4 yrs old right?

 

I do now!!!