having removed one cat on each side in a 99 i can tell you it will make a BIG difference. I have the magnaflow system which sounded nice, but once i took the cats off it made the 1800-2200 rpm range VERY loud, and cruising is a bit annoying. The trucks are pretty loud with just the cats, and with the magnaflow systems they sound nice and throaty. Also watchout if you get the dual 2.5 you might lose some low end torque, but if you dont care it will look pretty nice.

 

I have had zero problems with my Straight piped cat on my 5.4. I gutted it out and welded a 3" pipe through it. That made my truck REALLY LOUD! I also have a flowmaster single in and dual out. With 4" tips to the rear corners.

 

Dont be like me and everybody else i know... go spend a bunch of money and get a system with mufflers and then spend more money the month after cutting them out because their not loud enough. Just do it right the first time and get cat back strait pipes. But dont go to big with the piping.

 

Having straight pipes after the stock cats will be the sound you are looking for, not overly loud, but definately louder than any muffled system. I have a 99 4.6L with high flow cats and true dual straight pipes angled out the back with 5X22" SS tips, now, if you want loud, then get my setup.....

I paid $160 for the true dual straight pipes
I paid $80 for 2 high flow cats
I paid $80 to get my high flow cats installed
I paid $90 for my 5X22" SS tips

Doing the straight pipes with stock cats, and keeping the stock Y will run you next to nothing.
Doing true dual straight pipes wile keeping stock cats will run you about $160 for all the install and piping.

 

headers to duals with flowmaster 40's non delta flow dumped behind the cab just in front of axle, with turn down tips

 

I don't understand how you guys can think a system with mufflers, especially ones like Flowmaster 40 series or something along those lines, could be too quiet, unless you're basing it on what you can hear from inside the cab. Most of these guys I hear run around this area in trucks that have put exhaust on with glasspacks or straight pipes, they're about deafening...a little too loud IMO.

 

Its not that that gets me, its the people that call flowmasters performance LOL. They flow less then most turbo mufflers, all they actually have is noise. 40series aren't loud though. The Walker Quiet flow passes over 500 cfm. Basically, they(flows) might be better then stock, but magnaflow, and any other straight through has them beat for performance.

 

i dunno i prefer nice sound over raspy glasspacks anyday

 

I'm just saying that they aren't as good as people say. As for the sound, I guess all I can say is with 700 horse in front of them, yeah, I like flows too, but on a stock engine, well I cut the inlet and outlets off mine for another project and tossed the mufflers after a week. As for the raspy tone, large diameter tips around 24" in length help that. In my case 6"dia. truck stacks hidden up behind the bumper.(similar to Black Cloud Diesel's bull hauler stacks.

 

I just got a Flowmaster 40 duals on my 2000 F-150 and so far I'm liking it. Just got it done today so we'll see what I'm saying next weekend. I did have it no muffler before and the pipe just ended right under the pass. door and it was pretty loud, but very annoying on road trips.

 

As far as flows go i wouldn't go with them if i were u. i've already made that mistake. I ran true duals with 2 flowmaster 40's ending at 2 4"x18" angle cut tips on the sides. The flows were way,way to quiet for me. It was like i hadn't really changed anything. I finally went back and got them cut off and now i just have straight pipes behind the cats. I like it a lot better. I've been considerin cut the back two cats off but i'll loss a lil power so i might try high flow cats instead. i like the sound but i want it a lil louder the only prob bein is that i tow a boat a lot and i don't want it to get to load.

 

I had the Flowmaster 40 series as well...and yeah...it got too quiet after a while.

I cut everything off behind the muffler and dumped it and was happy for another couple of months, then just cut the whole muffler off and called it a day.

Amen, been there done that.

And keep the pipe size around 2.25 to keep from losing torque.

 

For what it's worth - I like a Flowmaster long-tube headers, an "X" pipe, Thrush glas-paks (true flowthru), next size up pipe and 24" X 4" tips for a deep but quiet rumble but smooooth sounding. I'm not too fond of the Honda 'bumble bee" rattle. It will get noticed - people will ask, "what engine?"

 

I went with 2.5 inch pipes off the headers. Two universal cats. One cherry bomb. Ran a y-pipe off the cherry bomb and put two custom burnt tips on it. Its a low throaty sound but consistant. Doesnt bounce around. Many good responses during drag races compared to other trucks. I spent 1100 because I went with magnaflow and rbp. Just run standard pipe and paint over it. Way cheaper.