2thousand5.4

I'm looking in to getting a set of high flows for my 5.4 and I have a few questions (yes I have already done my research so don't bash me please)

What cats do I replace with hiflows? The most reward 2 or all 4?

Any other brand than magnaflow that has a better price that is good quality?

How much louder/deeper should I expect my exhaust to be?

Will I get any drone? (I don't have any with my magnapack right now)

What's a good price for a shop to cut out the old ones and weld the new ones in (not including the price of the cats)

Should I get any CELs with the magnaflows?

Do I need o2 fowler's or whatever they are called to avoid the CEL?

Right now I have a SI/SO magnapack that I clamped on 2 months ago. I just cut out the old muffler and clamped in the magnapack and kept the stock tail pipe and exit. Anyways its just not loud enough for me right now. Other than that I love the magnapack its loud on acceleration and there is no drone at all when cruising, you almost cant tell its there.

Jbrew

Just axe the downstreams (larger ones) replace with a section of 2.5" pipe and your set. You now have HF's. Just leave the O2's alone, don't even disconnect the connectors if you don't have to. Your set! As long as the Y is still tight when your done and you haven't screwed w/O2's, your still within programmed parameters.

If your going with headers, -= it's different

If your using a tuner, - void this post.

2000/5.4/4x4

I took off all 4 cats, I just run high flows now but I need to get new o2s now and my right manifold wasent replaced so that needs to be done now, it sounds good barely any drone depending on rpm, on highway you can barely hear it but if I turn over drive off it's like a pack of bikers behind me lol

2thousand5.4

So you don't have any o2 sensors in right now? And just 2 high flow cats? Just curious what muffler are you running.

[MENTION=113]Jbrew[/MENTION] I want the cats so I don't smell

Jbrew

You won't smell. - Well your exhaust won't anyway lol. New High Flows are like your upstream converters (flow-rate and catalyst), - except, your factory up-streams are better than ANY HF on the market today, even new Mags. They don't make them like that anymore and the cats today aren't even close to being as good as your factory ups.

2000/5.4/4x4

No I have o2's but the one needs to be replaced it throws a engine code and causes a little less mpg+performance. Running a Maggie muffler si/do to 3.5inch tips it sounds wicked not to loud, once I get my manifold gasket fixed and air intake it'll sound a bit better, if I had the cash I would grab some headers too.

2thousand5.4

So a pipe in replacement of the downstream cats wouldn't cause my exhaust to stink? Will I still be able to pass emissions? And it wouldn't be like crazy loud with No cats and a magnapack?

2thousand5.4

What size is your Maggie? I don't have the money for headers right now but they are on the wish list

Jbrew

Nope.

Yup.

It would with no cats and the factory tune, - would run like garbage truck lol.

That's why you keep the upstream cats as I said.

2thousand5.4

I'm not gonna need a tune will I? I don't have that kind pf money right now