I just got a 04 RX-8 6 speed. It has a K&N short ram intake system...and I just had a custom exhaust made, which leads me to my important question, please help. I kept the cat and the resonator for now atleast and this muffler shop welded a 3 inch pipe from the resonator into a 2.5 inch Y pipe which goes to some exhaust tips. Now one person told me that 3 inch is too big for non turbo but I saw that companies sell 3 inch exhaust systems for this car and others tell me 3 inch is fine. Now my question is, is that 3 inch from resonator to a 2.5 inch Y pipe to exhaust tips fine? I shouldnt lose power right with this mod right?

P.S. Yes I dont have a muffler, goes from the Y pipe to exhaust tips, it actually sounds really nice.

Please help me guys, thank you in advance! Love the car so far

 

So you have the cat and resonator still in place, then NO MUFFLERS, just pipe to a 'Y' and the tips?

That's gonna be HELLA loud......


S

 

Yeah it is loud, but your right i have the cat and resonator still and just a 3 inch pipe from the resonator to a 2.5 inch Y pipe to the tips. So i shouldnt lose any horsepower or torque by doing this right?

 

only way to tell for sure is a before and after dyno...

 

think of parallel pipes like this though...

2x2.5 inch pipes next to each other = total flow capacity of a 3.54" pipe

 

Exhaust gas is cooler at the rear, the pipework should be larger at the front(at the cat) not the back to keep gas velocity up.

 

Yeah but when you decrease diameter in any way you create turbulence. On no performance car will you find a header that starts with a 3" collector and gets smaller as you go towards the back of the car.

 

Well if you guys had to assume, would you say im losing more hp or torque then what the car had stock? I will eventually take the cat and resonator out but i cant right now, money issues. So please, should i atleast of gained some torque or power then stock with this exhaust setup?

 

The biggest cork in your exhaust system is still in-place.

 

both of them.

beers

 

So with having the cat and resonator but with 3 inch piping to a 2.5 inch y pipe to the tips didnt make me lose horsepower or torque right? Keep it simple words please, lol...Did i gain anything? I just want to make sure i didnt lose power from stock...

 

No loss in power.

 

O.K. Good, I just wanted to make sure the exhaust setup i got didnt make me lose hp or torque, so you think if anything i gained a little? I know the cat and resonator are restrictive but do you think i atleast gained a little bit of hp or torque?

P.S. I know that you said no loss in power which clears my mind up a lot! I was getting scared for a second, thinking that i just paid for a exhaust system to loose power...lol.

 

 

Most exhaust systems custom or not will not yield much power at all. You didn't lose any power I'd bet. But as far as gains I'd say 3-4 maybe and that's a BIG maybe.

 

Peak hp will be the same maybe +1-2hp but the midrange would have suffered, not much though.
Exhaust flow volume is never fixed, and what is a suitably sized flow path at one particular combination of rpm & throttle will be way too large at another point and too small at another.
I've had had a catback exhaust then added a hiflow cat & now run just the hiflow, it now produces the best of both worlds. No loss of power after 8500rpm & better midrange. Im not chasing the peak numbers, just a better spread of usable power.

 

quick question, the welding job that was done with my custom 3 inch to 2.5 inch Y piple exhaust system i had checked with two different Mazda dealerships and they both said that there is no leaks in the exhaust...Here is my final question with this exhaust system, the RX8 exhaust isnt hot enough to blow the welds right?

P.S. A quick map light question, i know the bulb it needs is a 224 or somewhere around there, now what would happen if i put in a 194 bulb for now until i find a 224? I already put the bulb in and it lights up fine, but want to make sure i wont burn my whole electrical system...lol.

Thanks in advance for the help.

 

?1 no.

?2 i have no idea what a 224 bulb is.. to my knowledge they are 194s.

beers

 

do it and then post vid!