I'm driving an 89 F-150 XLT Lariat with a 300 I-6. I'm working on various modifications here and there, mostly weekend do-it-yourself projects. What I'm hoping to do soon is increase my performance (and my gas milage I hope). I'm probably going to put in a K&N air filter, plugs are new so I'll leave those. The big thing on my list right now is the exhaust. I'd like to get a sport truck sound out of my engine. I know there are better choices for engines to be doing this with, but this is the engine I have, so I'm going to work with it any way I can. I was looking at a Gibson cat-back exhaust system (side exit, just in front of rear, passenger side tire) Anyway, any help on this subject would be greatly appreciated. I'm trying to keep this within an acceptable price range, I don't want to have to sell my internal organs to raise money. Being in college hurts my budget quite a bit, but I set aside project money whenever I can.

 

Mike, the 300 without muffler or converter is not very loud at all. For under ten dollars you can go to any auto store and buy one 21/2 inch muffler clamp and a 21/2 inch 90 degree turn out pipe. If your muffler is like mine it is just ahead of the rear axle. Hacksaw or remove the muffler. Install the turnout pipe just ahead of the rear wheel and you got what you ask for. A cheap and easy cat-back that works.

 

Chris-
Did you notice a gain in MPG or HP after cutting out the muffler? And does anyone agree this is a good idea or should I spend the money on a cat-back system?

 

I installed a Gibson 3-in. cat-back some years ago. It gives the truck a nice rumble, 1-mpg better, a real kick in the seat of the pants you can feel, and went on in a couple of hours on the original hangers. The hardest part was shortening the piece from back of the cat into the muffler. If I had to do it over the only thing I'd change would be I'd buy the system in stainless rather than aluminized steel and dual rear bumper outlets rather than side. If its loud you're looking for rather than tone, I think today I'd simply do as numerous posts recommend and lose the muffler altogether.
Eddie

 

Lose muffler altogether. You mean just cut it out and then pipe it out the side or back??

 

Gibson offers several styles of cat-back system. The simplest and cheapest back when I bought mine was their 3-inch diameter, aluminized steel, mandrel-bent setup which included a truly huge expansion-type muffler and a 3-1/2-inch chrome tip. The piping itself was routed as the original, emptying out the side of the truck behind the right rear wheel. I'd've preferred their rear bumper, dual outlet system, but I occasionally tow an RV trailer and I didn't want to take a chance on posssibly sucking exhaust gas fumes back in the truck through the slider rear window.
I'd read in some magazine where they tested this system on a Cherokee with a 4.0L inline-six with good results, including a nice exhaust tone, so I bought one when the original system rotted off at the turnout.
My boss liked my system so well he went out and had a Flowmaster system with piping both before and after the cat put on, with excellent results.
All of these cat-back systems from different manufacturers are competing to do the same thing, and I believe I'd do some serious apples-to-apples price shopping before I bought.
I personally haven't done the remove the muffler and let the cat tone down the noise number. I wish I'd thought of it three years back!
Try this: there is a flange at the rear of the cat connecting it to the muffler; separate the flange so the cat is dumping straight out, wire the muffler up out of the way, and drive around for a week or so and see if you like it that way.
Make sure you take a long highway trip somewhere to see if the drone is acceptable. If so, order some big-diameter mandrel bends from one of the header manufacturers, and put together a side system which dumps out the side of the truck in front of the right rear wheel; make sure to get it welded up at a muffler shop.
Eddie

 

>Chris- Did you notice a gain in
>MPG or HP after cutting out
>the muffler? And does anyone
>agree this is a good idea
>or should I spend the money
>on a cat-back system?
Sean:
Haven't accurately checked the mpg but it has not suffered judging from miles per tank. I noticed a definite increase in torque from letting out the clutch without any gas on up. Better acceleration and holds speed on hills better. It revs much easier also. I'm always tight on funds. If I had a V8 I might spring for the cat-back. But I very seldom spin my six past 2500RPM and usually not more than 2000 unless I'm cruising in 5th gear. So dropping the muffler was good enough for me. I bought a nice impact wrench, sockets and air ratchet with the money I saved. Why not try this first? (it's cheap) If you are not satisfied you can get the cat-back and let us know what the difference is in performance. The exhaust on my 96 was in good shape. So I dropped the muffler and spliced in a 30 inch section and kept the original stock tailpipe out the rear behind the tire. All the original clamps hold everything nice and tight. In front of the tire exit would be good to. The mud wouldn't collect like it does in the rear. I think the newer F150's exit in front of the tire from the factory. Let me know if you have any more questions. Chris...