Exhaust System w/New Converter

HendyPhoto · October 7, 2003

I am cutting off my Magnaflow system and replacing it with an original "Flows" dual flowmaster 40 Series system , and I was wondering if I should or can upgrade to a high flow catalytic converter at the same time. Is this a good or bad idea, and will it make difference on the sound? (I like it loud and mean!!)

Thanks!

MCourson · October 7, 2003

I think it all comes down to how much back pressure you are going to need, and how much you are going to lose with the Flowmasters. I went to a high flow cat on the 94 just because the original stuff was worn slam out. I replaced everything from the manifolds back with high flow cats and a magnaflow single in dual out. I did not notice any loss in low end power (at least what little the mighty 5 has ) I would go with the high flow IMO.

CMNTMXR81 · October 7, 2003

OUr cats from the factory aren't all that bad, but there is always rom for improvement. I'd recommend getting a high flow converter (like a Random Tech) vs. completely removing it as some insist on doing.

I'm thinking about trying something different than my Magnaflow's, but they just sound soooo d**n good!

HendyPhoto · October 7, 2003

Yeah, the magnaflow does sound good, deep and throaty, but I want something louder and the dual flowmaster exhaust has a really cool tone. I wish I could remove the converter, but it's illegal in this state and I wouldnt pass my emissions test! I dont know anyone who will pass it for me! I think my magnaflow actually sounded better before I installed the K&N GenII air system. I want my 496 to sound like a 496! Who knows, I may end up putting the magnaflow back on, but I want to experiment.

CMNTMXR81 · October 7, 2003

It's only illegal if you get caught.

Seriously though, many here do it and we have strict emissions testing. If you're state/region/whatever is like the Illinois and Wisconsin EPA's, they do an OBDII test now an evap test (the gas cap) and a visual. Now with a high truck you may have a problem with a visual test but if you should choose to remove them, simply get a set of O2 Simms to trick the downstream (S2) O2 sensors and your PCM will think the cats are there doing their job.

The OBDII scan test is a godsend and the states are blind to it being a performance tuners golden earing.

HendyPhoto · October 7, 2003

DUDE! That is very tempting!!! HMMMM, something else to think about, thanks!

stlmaj · October 7, 2003

I just recently went in to get my exhaust replaced on my 6.0 liter true duals. The new mufflers are Ravin 33 series, They have a low deep rumble at idle and really open up with massive amounts of volume. (sound) They are definitely the loudest muffler I've ever heard!!!! The first two days of having them on I had a cackling sound but they have calmed down quite a bit and now sound deep, loud aggressive and mean. I've heard duel Flowmaster 40's on a 6.0 liter and they are loud and sound awesome but are about half the volume that I have right now!!! Unfortunately volume isn't what I was after and the muffler shop put the wrong series mufflers on they where supposed to be 55 series. The 33's are just too loud for me but I think they are the loudest muffler I've ever heard and if I was 10 years younger I am sure it would be exactly what I would want!!!!

I left my factory cats and just changed the muffler and tailpipes. I soon will have my 33's replaced with 55's

Good luck

Matt

HendyPhoto · October 7, 2003

I will ask my muffler place about Ravin. He said he would cut off the magnaflow and hold up several different muffs/tailpipes to see what sounds the best to me. Ravin will be on the list! If I was 10 years OLDER, I would need it twice as loud (so I could hear it)!!! LOL

Thanks amigo

stlmaj · October 7, 2003

If I was 10 years OLDER, I would need it twice as loud (so I could hear it)!!! LOL
Thanks amigo

LOL I kinda like the loud exhaust but the family can't handle it on long trips!!

Good luck

Matt

irqfdm · October 14, 2003

Was your magnaflow a dual in, dual out? From the factory it comes with 2 pipes into the muffler and 2 pipes out of the muffler right before it Y's into 1 exhaust tip (pipe). That is what I did to my tuck. You could put 2 magnaflow mufflers on and have 2 seperate pipes coming out, with some oversized chrome tips. That would probably keep the magnaflow tone, and add the flowmaster loudness.

HendyPhoto · October 15, 2003

I now have a single flowmaster exhaust, that goes out to dual with 4" chrome tailpipes in the back. The muffler has dual in and dual out. I was thinking about getting 2 mufflers, but they told me it would kill my power becasue there wouldnt be any back pressure. I ended up getting 50 series, and l couldnt cut off the cat. converter because of the O2 sensors in it. OH WELL, I am still very happy with the setup I have. And yes, my magnaflow was a dual in, dual out, then a Y to a single 3 1/2.

Hacksaw Hilliard · October 15, 2003

Hmmmm, in many states you are not allowed to even touch cat until 50,000 miles or it goes bad. I know Oregon won't just let you just swap it out. And during the DEQ testing, they DO check underneath each vehicle with mirrors to see if the exhaust has been modified.

HendyPhoto · October 15, 2003

It's legal here for some reason, but I couldnt cut it off anyway because my check engine light would stay on continuous because of the O2 sensors, I WISH I could have though. That would sound COOL!

CMNTMXR81 · October 15, 2003

It's legal here for some reason, but I couldnt cut it off anyway because my check engine light would stay on continuous because of the O2 sensors, I WISH I could have though. That would sound COOL!

Not if you get O2 Simulators. They trick the PCM into thinking that the post cat (downstream) O2's are there and functioning/fluctuating/switching normally.

Problem is, when I was under there this past weekend, I was looking quickly but did not see a complete set of O2's which kinda bothered me. We have two cats on our trucks. There should be one before and one after each cat. Maybe I just didn't see them as I was preoccupied with something else.

HendyPhoto · October 15, 2003

Would there be a way to program the PCM, westers, stock, etc, so it wouldnt need the signal from the o2's? Or any other way to bypass it so I can cut the cat converters off? Yeah, you are right though, because of the way it is set up, it would be illegal to take them off. The place that did mine said they dont do visual inspection of the converters. It's all in the computer they hook up to the truck that gets the signal. (I am no mechanic, so I have no clue, I just take their word for it!!)