Straight Pipe Exhaust

[jdmkasey]

So I'm going tomorow to get straight pipe on my MSP.
I plan on keeping the first cat so I don't throw a code.
I have a few questions.

1.) Will removing the second cat cause any issues or CELs?
2.) What size piping should I use, I know stock is 2.25 so should I do 2.5 or 3?
3.) I also plan on removing the resonator, good or bad idea?
4.) Lastly and most importantly, will my car run lean due to less backpressure? Any chances of boost spikes due to less back pressure?

Don't want to hear 'oh go buy a $900 HKS exhaust'. I hate the farting sound that most cannons produce.
I've always run straight pipe on all of my turbo S Chassis' prior so thats my preference. Just wondering how the MSP will react to such as I've seen that this is a very sensitive car. :/

 

[Knox Joe]

Unless you have to get your car inspected, keeping the cat is a waste. Just get a non-fouler.

 

[jdmkasey]

Unless you have to get your car inspected, keeping the cat is a waste. Just get a non-fouler.

Sadly I live in North Carolina, an emission state.
I'd rather keep my car inspection ready than have to run around when its inspection time.
I've been told that removing both cats can cause overboosting :/

 

[destineal]

sell ur mid pipe and buy a high flow cat

 

[KrayzieFox]

1. One cat will be enough to keep you from throwing a CEL, just make sure the 2nd O2 sensor is downstream from it.
2. 2.5" should do, there's no sense in going up to 3" without a matching downpipe
3. If you're keeping one of the cats, you might as well keep the resonator. The exhaust won't be as loud, which will make it more tolerable and attract less attention.
4. If you have the stock ECU, you will not run too lean. The stock ECU is pig rich, so if this is your only modification it'll hardly even make a difference in terms of air/fuel ratios.

 

[jdmkasey]

1. One cat will be enough to keep you from throwing a CEL, just make sure the 2nd O2 sensor is downstream from it.
2. 2.5" should do, there's no sense in going up to 3" without a matching downpipe
3. If you're keeping one of the cats, you might as well keep the resonator. The exhaust won't be as loud, which will make it more tolerable and attract less attention.
4. If you have the stock ECU, you will not run too lean. The stock ECU is pig rich, so if this is your only modification it'll hardly even make a difference in terms of air/fuel ratios.

What do you mean make sure the second o2 is downstream from it. I planned on leaving it in its stock location which is already after the first cat. Is that ok?
Yeah I figured 2.5 is fine, 3" might be overkill considering I'm not making that much power, it'll just end up being more noise
I planned on taking the resonator out so that the spool can be more easily heard through the exhaust. That's the one thing I miss the most with my s14 is my car sounding like an 18wheeler LOL. Dont judge!
That's good, yeah I figured since it was pig rich that I would have some room to play with it a bit. I know people have put exhaust on MSP's and I know they havent all blown up due to not being tuned.

 

[KrayzieFox]

Yeah that's what I mean, just make sure it's located after the cat.

I do hope you're planning on upgrading the midpipe as well. If you use the stock one then there is no point in doing the rest since the stock midpipe is so restrictive with the two cats. A single high-flow cat will do, it's what I have on my car and I don't get a CEL.

And as far as the resonator goes, take it out if that's the sound you're going for. The performance gains from removing it are minimal compared to removing the cats, it's mostly there for silencing.

 

[Dcmason22]

What other advantage is there for getting a high flow vs. straight pipe, other than not getting a cel?

 

[Installshield 2]

No offense, but you're a bit unclear on what exactly you're trying to accomplish with all of this...and your question about backpressure is pointing at you possibly not understanding how exhaust mods effect your engine...

The most restrictive part of the stock exhaust is the factory down pipe...Its hard to recommend other mods if you're not planning to do anything about that...as in, a high flow 2nd cat, cat-less mid-pipe, or factory cat and midpipe...are all going to be so similar...why change any of it to begin with?

I understand you 'don't want to hear go buy X exhaust'...but you're saying you don't want a 'fart can' like sound, but are also considering removing the factory resonator?...

color me lost, sir...Are you after more power?...better sound?...what?

EDIT: Sorry, didn't realize the post above this was not the OP...but still confused as to what the OP is looking in to doing...

 

[jdmkasey]

Like i stated, I miss how my sr'd s14 sounded as far as turbo spooling.
Anyway I went to a reputable shop and got charge pipes done and found the answer to my question.
End thread.

 

[destineal]

All your questions were answered at the shop? You gotta post your findings bro for the future new owners that may be in the same boat as you one day.

 

[jdmkasey]

He pretty much said the cat(s) and muffler is whats keeping the spool sound quiet.
Which is true I remember how my s14 was straight pipe to an apexi style muffler.
And I'm soo not willing to cut off my cats, so it'll remain stock exhaust wise.

 

[Sport23]

I would keep the stock resonator or add an aftermarket one to prevent droning. For performance your best bet is to change the downpipe and midpipe (cats), for just a change in sound you may just want to delete or change the muffler.

 

[jdmkasey]

I would keep the stock resonator or add an aftermarket one to prevent droning. For performance your best bet is to change the downpipe and midpipe (cats), for just a change in sound you may just want to delete or change the muffler.

I see in your sig that ur #378 i also have a titanium msp. How do I find out my number??

 

[KrayzieFox]

Call MazdaUSA and ask for the production number of your vehicle. You'll need to give them your VIN and they'll give you the number.

 

[destineal]

Or type your VIN number in google

 

[jdmkasey]

Found my number! #534