if i have full 2.5 in. exhaust with no cat, and weld on a 2.25in muffler would i lose power? i am thinking about welding on an ITR, s2000, or type S muffler on my 2000 SI to quiet it down. anyone ever do this? how does it turn out? anything would help... thanks!

 

1.) Put your cat on.

2.) The power loss will either be nonexistant, you will gain a little power, or you will lose a VERY tiny amount. Or you could lose a TON of power.

It's hard to tell. It's all based on your setup.

 

why put the cat back on?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by levison &raquo;</TD></TR><TR><TD CLASS="quote">why put the cat back on?</TD></TR></TABLE>

Because there is a potentially sizeable federal fine for driving without one, and you won't gain much power over running a 2.5" high-flow cat.

 

Definitely put the cat back on...all it does is pollute, smell bad, and make your car even louder.

I got my Magnaflow high-flow cat off of eBay for ~$65 shipped.

And I'm going to be doing the same thing you're talking about...but my exhaust is already 2.25", so I won't have an issue with that. I should have it done up pretty soon (using '07 Si axle-back on my '94 Civic)

 

Yeah, the only time it's good to remove your cat is when you're turbo'd or have a highly modified motor.

 

You might even feel a little more torque with an OEM muffler. The RSX-S muffler is pretty quiet but sounds good.

 

Go to ebay and get a high flow, my last 3 were from performancepeddler off ebay( 2 1/4, 2 1/2 and a 3 inch), You can get one to your door for around 50 bucks. The high flow flows and sounds about the same as a straight pipe, but keeps you federally legal and adds a lil backpressure, Which you def need a little on a Honda

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ke98248 &raquo;</TD></TR><TR><TD CLASS="quote">Yeah, the only time it's good to remove your cat is when you're turbo'd or have a highly modified motor. </TD></TR></TABLE>


True...turbo motors don't put out quite the fumes. My dad runs a straight pipe on his '84 300ZX Turbo and it made a difference, but it doesn't have half the fumes as my car does (currently running straight pipe...stock cat got clogged and was beyond broke at the time, but I have the high-flow cat and Si muffler ready to put on, just gotta get my car to the speed shop )...and his car is only driven probably once a month, if that.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JKov240 &raquo;</TD></TR><TR><TD CLASS="quote">


True...turbo motors don't put out quite the fumes. My dad runs a straight pipe on his '84 300ZX Turbo and it made a difference, but it doesn't have half the fumes as my car does (currently running straight pipe...stock cat got clogged and was beyond broke at the time, but I have the high-flow cat and Si muffler ready to put on, just gotta get my car to the speed shop )...and his car is only driven probably once a month, if that.</TD></TR></TABLE>

The amount of "fumes" have a lot to do with how your car is running. With all else being the same, a turbo car will put out the same amount of pollution as it's non turbo counterpart (at idle). Turbo cars tend to put out MORE emissions once the turbo spools up. More air+more fuel = more exhaust gasses. Those are all general statements...it all depends on how the car is running, tuned, etc. etc.

Putting on a test pipe for a street car really isn't worth it when it comes down to it. If one day the air gets polluted enough that you can't breath....even gaining 20 more HP really wont be on your mind.

Breathing&gt;HP.

Plus, with most honda NA setups for the street....you're looking to gain MAYBE 2hp if you deviate from the stock cat. At that point, even a high flow really isn't worth it.

 

I seem to remember reading somewhere that turbos are more enviromentally friendly...I'll have to look for that.


I know that test pipes aren't worth it (done both...can't tell a difference except in sound levels), but on his turbo car it REALLY opened up the exhaust (especially on an almost 24 year old car) and makes good power on a stock motor

(300 to the wheels and 12.60@112mph)


EDIT: I've looked around and can't find anything...must've imagined it or something


Modified by JKov240 at 8:49 AM 12/12/2007

 

The only reason I could think of that turbo motors could be environmentally friendly is because of their power density.

For example: A 200Hp SR20DET vs. a 200HP 5.0L mustang motor. The mustang motor was known to run dirty dirty anyway. When you have a BIG *** motor putting out very low power numbers, you know that there's a deficiency of efficiency (i like that slogan lol). The smaller engine will simply put out less harmful emissions when you're driving normally because it's a smaller engine. Less compression also means less NOx emissions. The power potential is there....but it's still a small, clean running engine when your right foot isnt on the ground.

Once you step on the gas hard, though, it becomes hard to tell. I think a small turbo motor is cleaner than a large NA motor that puts out the same or close to the same power level since the turbo motor really isnt "trying" till you really push the gas down to find out it's power level.

Kinda get what i'm sayin?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Padawan &raquo;</TD></TR><TR><TD CLASS="quote">

Because there is a potentially sizeable federal fine for driving without one, and you won't gain much power over running a 2.5" high-flow cat. </TD></TR></TABLE>

I don't know about a federal fine, maybe a state charge or something.. In NY if your car is earlier than '87 you don't need a cat. Lots of people that aren't OBD-II gut their cats so technically "it's there" - but it doesn't do anything. Obviously in OBD-II that would throw a CEL. And since no inspection station wants to check the volume of your catalytic converter to see if the honeycomb is still in there, it goes overlooked and uncared about.

In any event - yeah - put your cat back on, there's no difference with or without it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B serious &raquo;</TD></TR><TR><TD CLASS="quote">The only reason I could think of that turbo motors could be environmentally friendly is because of their power density.

For example: A 200Hp SR20DET vs. a 200HP 5.0L mustang motor. The mustang motor was known to run dirty dirty anyway. When you have a BIG *** motor putting out very low power numbers, you know that there's a deficiency of efficiency (i like that slogan lol). The smaller engine will simply put out less harmful emissions when you're driving normally because it's a smaller engine. Less compression also means less NOx emissions. The power potential is there....but it's still a small, clean running engine when your right foot isnt on the ground.

Once you step on the gas hard, though, it becomes hard to tell. I think a small turbo motor is cleaner than a large NA motor that puts out the same or close to the same power level since the turbo motor really isnt "trying" till you really push the gas down to find out it's power level.

Kinda get what i'm sayin? </TD></TR></TABLE>


Got ya

I guess it's one of those things I THOUGHT I remembered reading/hearing, but was mistaken...oh well