Two weeks ago I put A flowmaster muffler on my '95 F250 with the 5.8L. I was expecting something a little... louder than what I got. I didnt touch anything from the cat forward and only have one flowmaster on it. Some people have told me to rip out my current system and add the other flow I have sitting in my basement (I wanted to put both on but since my dad thought it was going to be too loud he wouldn't let me) Other's have told me to buy a Low-Flow cat (which my dad says will kill the preformance gained by any new exhaust parts). I'm only 17 and Im on a pretty small budget. If I already have the other flowmaster but not any of the pipes or adaptors to make a dual after the cat, whats probably the best bang for my buck when it comes to sound, and I want to keep it legal for MA inspection, so removing the CAT is a no go.

 

high flow cat.. with flowmaster 1 chambers if you want something loud.. or the 40 series is ok.. does it sounds like mine??

remember cats muffles the sound more.. so with cat you cant expect something loud... exept.. straight pipes after cat is a common setup to

http://s198.photobucket.com/albums/aa217/demon6696/?action=view&current=latenightsoundclip.flv

mine is a single 3 inch NO CAT flowmaster 40 Delta flow

http://i198.photobucket.com/albums/aa217/demon6696/DSC00631.jpg

http://i198.photobucket.com/albums/aa217/demon6696/DSC00632.jpg

http://i198.photobucket.com/albums/aa217/demon6696/DSC00634.jpg

 

The second flowmaster will make it quieter, so stick with one muffler. A high flow cat will make it louder and perform better, esspecially if the cat on the truck is old and starting to plug.

 

My truck just failed emissions today for the second time in 2 months, and the NoX was over. The amount it tested for was higher than it was 2 months ago so I think the cat is clogging. I am thinking about hollowing out the cat so it will still pass visual inspection and hopefully still pass emissions since the clog is removed. This will solve the noise problem if anything.

 

hey sry about the emissions test, here in wyoming there are not any tests I took everything from the cat back off my 460 and straight piped it a little to loud got pulled over cause they thought i was hot rodding it lol. Oh yah im only 16 so thats why the such a crude set up (i just cut my exhaust off with a saw and called it good).

 

The idea of hollowing out a cat has been discussed a lot on this site. When you clear out your converter it will create an expansion chamber, which will have a negative effect on exhaust flow. I have known a couple people who have done this and both rigs did not sound as good after. I thought about doing this to my old cat when it went to hell, but decided against it because of the possible negative effects on exhaust flow and the fact that if your converter is old and bad, there is a good chance the outside will start to rust out soon and you will have an exhaust leak on your hands.

Also, your chances of passing an emissions test with a hollowed out cat are not the best. I would recomend getting a high-flow cat. If you do end up getting a new cat, check the your codes and make sure you do not have a bad O2 sensor, a bad O2 sensor can kill a cat real fast (that is what happened to mine), and if you have any codes related to the O2 sensor, replace it with the converter.

Good luck passing emissions, I am sure glad that I do not have to deal with them!

 

Your truck should have 2 cats. Take the second one off and run a 3 inch pipe from the front cat back to the Flow. It will sound better.

 

My F350 only has 1 cat. If you have my setup Id just get a high flow like this from ebay for cheap, If you can use this to make it dual http://cgi.ebay.com/ebaymotors/CATAL...QQcmdZViewItem

Thats if your y pipe goes into 1. I have used these cats before on a bunch of friends cars, no complaints. http://cgi.ebay.com/ebaymotors/Stain...QQcmdZViewItem My F350 is true dual factory untill the cat. If its my style I did this,

Where the flange is that goes 2 the muffler is where the stock cat would go on my truck. If if you this style they do make a adapter on ebay that will bolt 2 the flange so you can run a standard cat like i posted above. If you have the other style Y pipe just remove the last cat, put a new one on, pass inspection then take it off and put pipe 2 your flowmaster. You will still have your front cats, but lose the back cat. Post some pics of how yours is now and then we can better tell you how to mod.

 

If his truck is over 8500 GVW, it will have only one cat and a setup similar like mine or 95F350XL's. If under 8500 GVW, it will have two.

By the way 95F350XL, where did you get the flange you used to mount up to your muffler. I am planning on using Flowtech longtubes and making a "y-pipe" like yours so I can bolt directly up to my cat. I was thinking about cutting the flange off the factory y-pipe if I could not find a new one, but I would prefer to get a new one.

 

I actually made it. The one on the stock cat flange wasnt big enough for 2 2.5 pipes. I traced out the cat peice on carboard, then the bolt holes, then figured out where the outter end of the pipes were using the stock cat gasket. Then traced it all out, cut it out, transfered it to metal, cut it out, then welded in the 2.5 pipe. It wasnt too hard, and im not usually good at that sorta stuff lol.
Here is where my 02 is just incase yours is the same. I put it into 1 pipe vs. in the middle of both like the stock one. It was just easier.

Oh here is my stock cat setup. lol getto but passes inspection.

 

Thanks Guys,
Raider, Im only 17 so I know what you mean by only being able to get a crude setup

My truck is over 8500 GVW so it only has one cat. I think a bad TPS was causing my engine to run way too rich and that was what killed the cat. I fixed that but it still did the damage. My system right now is a single pipe out of the cat back to a flow, but I do have another flow sitting in my basement I could stick on if a high flow cat made dual pipes.

 

ive thought about cutting off both of my cats
(so i have true duals) and either straight piping it, or putting a cross flow muffler on it. either way if i cut off both cats or one it sound good

 

I would cut off the cat, however I would fail inspection, but it would sound good it you cut them off and had a cross flow muffler behind it.

 

My truck is 8800 GVW (F250 extended cab) w/ 5.8. Here are some pics

The cat has a 4-bolt flange which has a 2-into-1 adapter (2nd photo). Cat has single outlet (I forgot to check if it's 2.5" or 3"). Then single pipe in to Flowmaster 40 with single outlet.

Autoparts warehouse shows an Eastern 30801 cat for $459.00 (almost as much as I paid for the truck!). Ouch.
1) Are any of the high-flow (and reasonably priced) cat's compatible with the 4-bolt flange on the inlet?
2) If not, would it make sense to cut of the flange and weld two smaller cat's in parallel to each of the two pipes that come into the flange from the engine?
3) any other ideas?
4) If I don't have any check-engine light issue, can I assume the oxygen sensor is ok...or should I replace it just to be safe?
Thanks!

 

hey reeds, where does your exhaust go after the muffler? does it just end there or did you put on some sort of piping. and where can one find such piping to make homemade systems like these? i have a 96 250 with that same single big *** cat setup, to that giant stock muffler and dual 2 inch exit pipes. i think i'd be interested in that above mentioned adapter to go from dual pipes from the manifold to a single inlet high flow cat (stock is dual inlet cat). and how do you hang all this, do you have to buy new hangers?