Off-road vs. Cats for a 99+ 4.6 ????????? Help!

Andrew_5.0

Founding Member
Jul 21, 2000
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CA, USA
I've decided to keep the 99GT and start modding it. Gotta start with the basics. ON A STOCK MOTOR, which it will remain, is an o/r h/x pipe the way to go?? I have heard sooooo much controversy on this topic it is driving me crazy. So I need some facts guys. I want to put an o/r h-pipe on there tomorrow, but I am skeptical.

The whole loss of low end w/ an o/r pipe is what I hear. One of my local shops (B&D Racing in Los Angeles) says very few 4.6s hes done run well w/ o/r pipe.

So... if catted route, whats the cheapest route to go?

If o/r route, do I go x or h? Ive heard x sounds like crap.

Thanks
 
if emmisions is not a problem, go o/r. there is no reason it shouldn't run well./

a good X pipe will beat any H pipe in low end and top end. the X pipe is the way to go for performance.
 
DBMSTNG said:
if emmisions is not a problem, go o/r. there is no reason it shouldn't run well./

a good X pipe will beat any H pipe in low end and top end. the X pipe is the way to go for performance.

The first part of what he said is correct. The second part is the most Bull**** I've ever heard. X-pipe moves your power up higher in your power band hence taking away low end torque but giving you more high end horsepower. An H-pipe will give you more low end torque than an X-pipe but not as much top end horsepower. Just buy for the sound if you are planning on keeping your motor stock. Personally I prefer the chambered mufflers and O/R H-pipe sound but hey go listen to some sound clips and decided for yourself.
 
if you have emissions issues, and want a midway for H and X MAC makes a catted prochamber... rumble of the H with the slight whine of an X at high RPM and power gains comparable to most X pipes
 
Sick96Stang said:
The first part of what he said is correct. The second part is the most Bull**** I've ever heard. X-pipe moves your power up higher in your power band hence taking away low end torque but giving you more high end horsepower. An H-pipe will give you more low end torque than an X-pipe but not as much top end horsepower. Just buy for the sound if you are planning on keeping your motor stock. Personally I prefer the chambered mufflers and O/R H-pipe sound but hey go listen to some sound clips and decided for yourself.

:stupid:
 
Emissions is of no concern. I care only about performance and sound.

I have also heard that H will give more low end torque (more back-pressure), and that the X will give more upper-end power.

What I wanted to run across everybody was my concern that power would be sacrificed.

Also, how does the X sound compared to the H? I have heard that X on 4.6 sounds like garbage. But if one was to go with a "true" X, like dr. gas or magnaflow, then it sounds better.

I have never heard anything negative about how a H sounds, obviously.

thanks!
 
You will not have as much torque down low when you change the stock h pipe to an off road h pipe. The sound is killer though! If you plan on puting gears in then dont worry about torque loss, just do what I did change to an offroad h pipe then put in 4.10 gears. Dont let anyone tell you different. you will notice some torque loss down low.
 
jrc_03_gt said:
You will not have as much torque down low when you change the stock h pipe to an off road h pipe. The sound is killer though! If you plan on puting gears in then dont worry about torque loss, just do what I did change to an offroad h pipe then put in 4.10 gears. Dont let anyone tell you different. you will notice some torque loss down low.

When I put on my O/R H-pipe it seemed like there was gains throughout the entire powerband. If you put on an X-pipe you will sacrafice low end torque. H-pipe you wont sacrafice anything just wont get the top end gains of an X-pipe. Most people who buy for performance go with an O/R X-pipe and a straight through muffler.

As far as sound goes, only you can decide what sounds best. IMO magnaflow X-pipes sound like ****. Best sounding X-pipe I have heard is Bassani O/R. Dr. Gas sounds pretty good also its alot deeper than most of the other X-pipes. Magnaflow X-pipe is alot raspier. H-pipe will give you a deep rumble, but when you get on it, it gets pretty loud. My personal preference is chambered mufflers with O/R H-pipe but again just go listen to some sound clips and decide for yourself.
 
Sick96Stang said:
When I put on my O/R H-pipe it seemed like there was gains throughout the entire powerband. If you put on an X-pipe you will sacrafice low end torque. H-pipe you wont sacrafice anything just wont get the top end gains of an X-pipe. Most people who buy for performance go with an O/R X-pipe and a straight through muffler.

As far as sound goes, only you can decide what sounds best. IMO magnaflow X-pipes sound like ****. Best sounding X-pipe I have heard is Bassani O/R. Dr. Gas sounds pretty good also its alot deeper than most of the other X-pipes. Magnaflow X-pipe is alot raspier. H-pipe will give you a deep rumble, but when you get on it, it gets pretty loud. My personal preference is chambered mufflers with O/R H-pipe but again just go listen to some sound clips and decide for yourself.
There is no way in he11 you can put an off road h pipe on a 4.6 stock motor and not have any torque loss down low. I have had two mustangs with off road h pipes both of which were 4.6 stock motors and each time they lost torque down low.
 
jrc_03_gt said:
There is no way in he11 you can put an off road h pipe on a 4.6 stock motor and not have any torque loss down low. I have had two mustangs with off road h pipes both of which were 4.6 stock motors and each time they lost torque down low.

If I did lose low end torque I didnt feel the difference. I didnt get a dyno to show I lost or gained torque so I couldnt say for sure but just by SOTP it didnt feel like I lose anything.
 
How about SLP X pipes, how do they sound.I plan on going with a SLP catted X and a magnaflow cat back.Only deal with not having the cats is the stinking engine light coming on, and i DONT feel like spending $70 for MIL elims or $400 for a diablo flash tuner.I would rather pay $50 extra for the catted version and loose a HP or 2 and not have anything to worry about.Now if O/R adds more than 5HP then I may just spend that 70 LOL.
 
cats suck up some power, but as with all mods, the gains are relative to your other mods, it could be 2 it could be 20.... get the mils... check the thread a few down on how to make your own for a few pennies