[GTSilver]

I asked this question in the 99-04 modular forum but no one responded. Should i take out my Hi-Flo's and go completely off-road? are there any power gains from having no cats as opposed to Hi- Flo Cats? Did i waste my money on Hi-flo's?

[99mustang232]

what hi-flow cats did you use, some are better flowing than others...

[GTSilver]

i beleive they are magnaflow cats. the sound is absolutley incredible...its deep and roaring around 2000-3500rmp and on take off you can hear it for a few blocks...i havent heard a mustang that sounds like mine ever...i dont want to compromise that sound if i dont have to.

[ckthecerealkiller]

Unless you are going to have some major work done you aren't really going to see more the 1-3 horse. Plus in my experiance the cats keep the sound nice and deep. I'd say keep the cats and pass emissions.

[ben1380]

Get the hi-flows...save the earth

[Drgnracin72]

tree hugger!

[ben1380]

LOL!

I actually had an offroad prochamber on my GT, so Im one to talk

[Bill]

Some of these Hi-Flo cats today Flow so well that there isnt that much of a difference between the Offroad and Hi-flo midpipes.

[99mustang232]

exactly

[cobralini]

So..... What brand is best or gives the best flow? I would like to get that snap, crackle, pop sound when I let off the gas or down shifting.

[GTSilver]

i had a 95 f-150 work truck 4x4 with a 302. i had 1 flowmaster with two dumps and no cat. that truck sounded just as mean if not meaner than my stang. it was a manual trans and it had that metally poping sound especially when shifting it was sick! if you want that sound go with the flowmaster 40 and no cats.

[cobralini]

My car cam with flows and off road H. I had put the original mid pipe on to pass emissions but left the smog pump off.....passed with flying colors. I want alittle more noise so I will go with a good set of high flows but I may look into getting the x instead of the h. The x has more of a controlled sound to me on the 4.6 cobra I had but I am not sure what to expect out of my 5.0 ...... you really can not beat that offroad sound but I do not want to look over my shoulders cause my car was SUPA LOUD with the off road h pipe on it.

[Haggis13]

Sweetest sound ever is a Bassani off road x-pipe with the 2 chamber flowmasters. REAL loud on the highway though - your ears'll buzz for a good half hour after a good run.

[Screemin3o2]

I don't really care for x-pipes, they are a little too raspy for me. When you are not talking about a serious horsepower engine, it really all depends on the year. For your year model, or the most part between hi-flow cats to offroad or h-pipe to x-pipe you are going to see a very minimal hp increase. Your car isn't that old so the cats aren't getting old enough to really cause too much of a restriction. I would go with whatever sounds better.
I read an article and had it confirmed that SLP or Hooker (don't remember, was a little while ago) made many different styles of exhaust systems for a brand new c6 zo6. Each style barely made any sort of increase in power and even a few decreases. This shows that companies are really starting to make their exhaust systems able to flow very well from the factory. A lot of people may disagree but my opinion is if you look at the results and the science of it, you are going to get a very minimal gain if you are dealing with a stock engine on a newer car. Most of it is based on sound nowadays. By the way I dont think your cats are what is giving you a deeper, louder sound. If you want a loud, deep and hollow sound, get a prochamber.

[GTSilver]

i just took off my hi-flos and i think i might have lost power going with the strait...did i or am i just paranoid?

[raceruler03]

is it an x/h pipe or is it just straight pipes?

[Screemin3o2]

Originally Posted by GTSilver i just took off my hi-flos and i think i might have lost power going with the strait...did i or am i just paranoid?

You are paranoid if you switched from a catted pipe hi-flow or not to an h/x pipe.

[GTSilver]

Originally Posted by Screemin3o2 Originally Posted by GTSilver i just took off my hi-flos and i think i might have lost power going with the strait...did i or am i just paranoid? You are paranoid if you switched from a catted pipe hi-flow or not to an h/x pipe.

i switched to hiflow cats to no cats with my x-pipe.

[Justincredible]

Originally Posted by ckthecerealkiller Unless you are going to have some major work done you aren't really going to see more the 1-3 horse. Plus in my experiance the cats keep the sound nice and deep. I'd say keep the cats and pass emissions.

+1

quote="GTSilver"]i just took off my hi-flos and i think i might have lost power going with the strait...did i or am i just paranoid?[/quote]

My best friend has a dyno shop. To settle a simialar debate...we dynoed a 99 GT that had an off-road h-pipe, 2 chamber flows, and dumps.

We swaped in a h-pipe with "hi-flow" cats, Magnaflow mufflers, and a full set of 2.5" tail pipes.
It actualy made more torque from 3000rpm up and the "average hp" acutaly went up. The tail pipes lost about 7 hp in the lower rpms.

Needless to say...we all were very surprised by the results. If anything, we expected the tail pipes to hurt the higher rpm hp. Go figure.

[Screemin3o2]

Yeah it all depends on what type of pipe you are actually using and if that's just the way it is with your car. With so little mods it shouldn't be much of a difference to be noticed I wouldn't think.