How different is it from stock? Cat back and Roush tip? Thanks

------------------
White 97 XLT SC 4.6, 4X4, 3.55ls, door cracks, tow pkg, long bed, Rhino liner, Owens running boards

 

The only difference is the split stainless tips. The dealer couldn't tell me so I called Roush. Wanted to find out before I pulled out muffler and made change. 2 1/2" from Y to tip.

------------------
98 Nascar Edition, Superchip, Airaid, Flowmaster 70 series, bedliner, in bed tool box, Profile bug deflector and window vents, Class III receiver hitch.

 

Thanks. I saw a new one on a dealer's lot in 98, and it sure didn't sound like other F-150s. Does the Roush tip make that much difference in sound? If so, I want one.

 

I don't know, I guess it is the tip. I drove another 98 XLT supercab before I drove this one and thought the Nastruck had a little more rumble but nothing you could hear over 150' away. I replaced the muffler only with a flowmaster 70 (their biggest and quitest series) at idle it is almost identical but you can hear it when you are under a load or heavy acceleration. I could feel a little improvement in performance, especially while towing.

------------------
98 Nascar Edition, Superchip, Airaid, Flowmaster 70 series, bedliner, in bed tool box, Profile bug deflector and window vents, Class III receiver hitch.

 

Johnny, did the Flowmaster affect your MPG? and is it loud inside the cab at 70 mph? Thanks.

 

Can't say that it improved mileage. I probably average around 17 mpg on road. Best tank was 19 and that was before the flowmaster. Don't think it hurt the mileage. At 70 you don't hear it unless you pass someone. There is no drone at any speed. Most people think it is too quite. I wasn't interested in the sound as much as I was in performance. I studied the message boards and ads for several different mufflers and liked the flowmaster. The 70 series is normally put on motorhomes and larger trucks and I had a hard time finding one with 2 1/2 in and 2 1/2 out. No one in Houston had one, in fact I couldn't find one in Texas. Ended up getting it out of Ca. It is a big heavy muffler, heavier than the stock muffler and it fit into the present system with almost no modifications. One of the things it does is draw a lot of heat out of engine compartment and heat shield should be used, the stock heat shields were in the right place already. If you are thinking about the 70 series, get ready to spend around $100 for it, not including installation. I am happy with it, performs as claimed.

------------------
98 Nascar Edition, Superchip, Airaid, Flowmaster 70 series, bedliner, in bed tool box, Profile bug deflector and window vents, Class III receiver hitch.

 

Tenderpaw, the stock pipe, from Y thru tailpipe on 97 thru 99 and maybe 2000 models is 2 1/2" for the F-150s. I'm not sure about the Expeditions but I think it is the same. I don't think anyone would be offended by the exhaust note. At WOT it is a deep mellow sound. Just enough to tell it is not stock.

------------------
98 Nascar Edition, Superchip, Airaid, Flowmaster 70 series, bedliner, in bed tool box, Profile bug deflector and window vents, Class III receiver hitch.

 

I too agree with Johnny, I have a 98 f-150 4x4 with the 5.4 liter engine. I studied the board and got input from others that installed cat-back systems. The final result for me was to install the Flowmaster muffler (three chamber). I did so at the advice of a person that owned his own high peformance truck shop and raced on the side when he was off.

I was ready to buy the Gibson system however, he told me that I would loose torque on the low end. I wanted something that would not mess with the emissions and increase performance. Noise was a factor too. I didn't want anything that sounded like I was landing an air-plane when I was driving.

He told me that the flow-master would increase flow getting rid of hot exhaust gases and lowering engine temps. In addition, I would see increased performance too without sacrificing the low end torque.

I took his advice based on the fact that he could have made an addtional $150.00 selling me the Gibson. I paid $95.00 and had it installed.

Slight loss of torque (I mean so slight that I shouldn't even mention it) and the performance was very noticable in terms of acceleration through the gears and high end passes. No more high revs and go nowhere effect.

Gas mileage was a non-issue, not enough to mention.

Hope this helps--- regards,

------------------
Rick Medina
Las Vegas, Nevada

 

Hey Johnny-

Is your stock tailpipe 2 1/2 inches. I was thinking of installing a flowmaster 70 series on my wife's Expy, and was wondering if it is worth it in terms of performace. Since its her car, it must stay quiet. A little full throttle noise is OK.

------------------
2000 Expedition XLT, 5.4, 3.31 Rear axle, 4R100, no other mods