Is it worth removing the CAT.?

[Ghostgt]

I was wondering if it is worth removing the cat. and running 2 1/2 pipe to my dynomax muffler? Also how much louder would it be? Thanx.

[prisen]

go 2.25" max, do not remove the cat. Put a high flow cat in. No cat/resonator would be LOUD.

Unless you have forced induction (ie. turbo/supercharger), you need backpressure.

[TA^Guy]

On a naturally asperated 4 cylinder I wouldn't go above 2.25" diameter.

And removing the catalytic converter will reduce your lowend, especially on a 4 cylinder. If you feel the need for more exhaust flow I would purchase a high flow cat, or atleast a electric exhaust cutout like a quicktime cutout, and mount it before the converter. This way you could open it up when your racing and close it during normal driving so you don't get a headach.

[ferran586]

Can someone tell me why it is not good to go more than 2.25. I was thinking going with 2.5 myself but if someone can tell me why I shouldn't I would greatly appreciate it.

[TA^Guy]

Larger diameter pipe reduces back pressure. But if you reduce backpressure too much on a naturally asperated car you'll lose lowend torque by ruining the scavaging effect of the exhaust.

[ferran586]

:thanks: TA^Guy, you just peruaded me to go with the 2.25".

[Colin]

If you use an exhaust pipe that's too large a diameter you can actually lose power . This is due to the reduced exhaust gas velocity . The speed that the gas is flowing through the pipe will slow down and low end torque will be lost . Very high RPM power output may improve somewhat , but how long would you actually use it in daily street driving ? TA^Guys recommendation of 2.25 pipe is the best for your application . :D

[Themeneea]

how about the V6? whats the stock piping and whats a good pipe size to use?

thanks

[MJE95GAGT]

Not sure about SEs, but 99+ GTs are 2.25" crimp bent stock, if you are planning on only modifiying your car a little, 2.25" mandrel will be fine but if you are going to modify your car more, then I suggest 2.5" mandrel

[Colin]

Originally posted by MJE95GAGT
Not sure about SEs, but 99+ GTs are 2.25" crimp bent stock, if you are planning on only modifiying your car a little, 2.25" mandrel will be fine but if you are going to modify your car more, then I suggest 2.5" mandrel :agree:

[martopg]

Originally posted by 94greenga
I was wondering if it is worth removing the cat.

Well, I'd think so... if you leave it in there the fur might get into your engine and cause problems. And I think it'd be annoying hearing it whine every time its tail gets caught in the cooling fan... :lol:

Ok, lame joke :(

[L!m3]

With an CAI wouldn't it probably be better to run 2.5 piping? Sure it doesn't push the exhaust out faster than forced induction but it's better than the stock intake.

[HighwayProwlerz]

Don't remove your cat... just get a high flow cat. They put those on there for a reason ya know.

[99blackgt]

cant pass your emissions test without the cat

[Pte Socks]

yep, if anything, only remove the res. I know for my setup im getting a high-flow cat and no res with 2.5" mandrel bent piping.. I know that because I only have a CAI initally, that im going to have some low BP but im going to be getting headers as the next mod so that should help out that little problem.

[Old Guy]

Just my 2 cents but 2 1/4" Mandrel is plenty unless you're planning on going SC or Turbo even with headers. Adding headers will give you more flow and reduce the back pressure even more.

Torque is the name of the game.

[Blackrider]

Even for a moded NA Setup 2.25 is to small. with headers head work, Intake ect. I would go with 2.5. What ever you lose in the bottom and will be made up up top. speaking from a pure 1/4 mile stand point. if you still want some low end torque for city driving then i would leave the stock cat on with 2.25. But i have no problem running around with crappy low end torque.

Speaking from a V6 Standpoint.

[Old Guy]

I agree when it comes to the mods you have done, but with only a CAI ...which is what most guys go with.. your top end gains won't offset the loss at the bottom. And absolutely 2.5 is overkill on a NA 4 banger.

I really doubt that you're running around with a crappy low end when I look at the times you're turning :)

[Blackrider]

Originally posted by Old Guy
I agree when it comes to the mods you have done, but with only a CAI ...which is what most guys go with.. your top end gains won't offset the loss at the bottom. And absolutely 2.5 is overkill on a NA 4 banger.

I really doubt that you're running around with a crappy low end when I look at the times you're turning :)

And can you Believe I was Pissed off at my times :lol: I still have stock piping on thats giving me a bit of Restriction.

the fact is that when you are running a farly heavy load of mods you dont want to go 2.25 it will restrict your top end way to much. There are other things out there that increase bottome end torque. such as compression, 1 point of compression is only going to give you 4% more power. BUT its where that power is created is the key. Increased compression does wonders for low end torque. having Higher compression and small piping is Futile. You need that flow espeshaly (SP) with headers up top, and 2.25 is really going to chock it off. Back Pressure is more in peoples heads I think.

Borla is a great exhaust system for running around the city not to loud Still offers a good deal of low end torque, But when you start into the heavy mods such as headers head work TB FI that piping and ( resonator:roll2: ) really becomes a problem.

SLP Is more from the Performance crazed people. It Offers an exhaust system that is waiting for mods.

It sounds like i'm contradicting myself but yes it has been proven that you lose low end torque with free flowing Exhaust systems BUT there are things out there that make up for it (Compression) and in the end you are going to need the biger piping.

Ow and I agree 4 banger + 2.5 = usless unless. http://www.j-body.org/members/tunedz/cars/1/

My Buddy Mike.

[1992grandam]

i got a question.....i have a 96 GA with the 2.4 and i was planning on going 2.5" becuase i do have plans for sum major mods in the future...(turbo) and when i do then i dont want to have to switch to 2.5" if i have 2.25. is this a good way of doing it or should i still just go with 2.25?

[matts]

i'd go with the 2.25. it'll be the best of both worlds :)

[Pte Socks]

yea, im still not convinced on the power of the 4 banger GA's. Sorry, but id still suggest 2.25" mandrel bent. One thing that should be mentioned is AIR FLOW IN NEEDS AIR FLOW OUT! this is important and probably what old guy is trying to get across. Put it this way, if you get an exhaust, you will want to get a CAI. If you get headers, then get a larger TB or P&P your manifolds and so on. This is the best combination for your mods. If you know and I stress, know, that your going to be majorly upgrading your car, then always be thinking ahead. I know I will need my car for a race car/ show car for my shop, hence I know I will be getting specific upgrades and I know what my final goal/ idea is. If you dont know, go the more conservative size to save yoruself the headache.