I currently have a flowmaster 44 SI/DO muffler with dual 2.5" mandrel bent exhaust pipes with 4" flowmaster rolled edge tips.

I have all four stock cats (2002 Supercrew 5.4L).

My question is: I want to know if I would gain any more sound out of my exhaust by changing out the bigger rear two cats with Magnaflow high flow cats (probably part #94106, the smaller universal ones). I don't like the idea of deleting the front pre-cats. I would like to keep it legal. Would just swapping out the rear two cats for hi-flows do anything at all for sound? Or am I just wasting my time if I don't plan on deleting the front pre-cats?

Thanks,

Brad

 

Yes you can do this. Its most prefered to scrap all 4 cats for what you can make and just use two hi-flows but the front cats do not restrict flow. The rear cats kill alot of sound. Removing them and adding hi-flows will really let your truck roar.

Replace your rear cats with 94106 Magnaflows for the ultimate sound gain.

It will sound very similar to Rich's truck ( Super 44, and hi-flow cats ). He hasn't been around lately so i'll post his video for him.
http://www.youtube.com/watch?v=ug6cC...e=channel_page

 

awesome, thanks man for the quick reply. Does that other guys truck still have the stock pre-cats too? true duals, or split at the muffler like mine? just curious...if you happen to know or not. His truck sounds just right in my opinion. I hope mine sounds like his when its all said and done.

thanks again, and I am definately ordering a set of the 94106's as we speak.

 

He has a single in, dual exit muffler. I think he ditched all 4 cats, I can not remember though.

 

Yes Rich has just the two hi-flow cats, 94306 models which are a hint calmer than the 94106s, your truck with 94106 cats and the pre-cats ( that dont really resonate sound ) should have him beat by a couple decibles. He has a 3" exhaust with a SI/DO Super 44.

 

I would NOT want to be louder than his

 

Same here, I wouldn't mind being right where his is at though, good volume on idle, respectable around 2500rpm accelerations, but then it will disturb everything under WOT. I'll be running them sooner or later so we'll find out.

 

Is that a 5.4 or 4.6?

 

5.4l

 

True that.

 

how would a magnaflow cat part number MPE-53005 flow comared to stock for a 99 with a 4.6?

 

Much louder? lol

 

Do not buy the 50000 series cats. They are not designed to work with trucks and SUVs with bigger engines than V6s. It would flow better, but that cat is designed for V6 engines. The 4.6L will not run well with it, eventually causing it to fail. That cat also is under the 4,250lb GVW rating, meaning it will not work on any vehicle that weighs more than that. You need the 94000 series cats that are meant for V8s, and have GVWs of 6,000lbs.

DO NOT RUN 50000 SERIES CATS ON A V8.

 

so a MagnaFlow 94025 is what I should be looking at?

What kind of performance can I expect to gain with replacing hte stock cats with these instead?

Thanks for the help

 

Yessir!