Well my Flowmaster kit DOR, Force II muffler has just been installed. The sound is deep mellow with hardly any interior resonance. It is everything I hoped for in sound. Step down on it and you know its there. The shop had some dificulty with the installation, a real tight fit over the rear axle. Any significant bump and the axle would hit the tail pipe. I notice that after I picked it up. Taking it back this weekend for the fixed. I was a little dissappointed that the kit did not fit but very satisfied overall and I do trust the mechanics. It appears to be minor problem. I would be interested in hearing if anyone else experience the same problem.
Ray Davis
1999 F150 SC 4.6, Black with Silver accent,Westin step bars, K&N air filtration. Flowmaster 17222 kit that was hard to fit.

 

Hi Ray,

Congratulations on getting your new muffler system installed. It does sound nice and looks great. I have noticed a minor increase in mpg since installation.

I did not install a 17222, but a 17137 Flowmaster kit. It is the same in that it is dual out rear, but for the 1997 trucks. In an earlier post, I described how I had to install two four inch extensions on each of the muffler outlet pipes (before the axle) to make the remaining piping to the rear fit correctly. As the kit came from Flowmaster, there was no way it would have fit. The tail pipe that exits to the left (between the differential and spare tire) would have hit the differential cover. Also, if you have a 4x4 with 17" wheels, you want to make sure the spare tire doesn't touch the left exhaust pipe.

I contacted Flowmaster about all of this. At first, I thought my kit was improperly copied. However, their specification measurement was the same length as my muffler. They did reimburse me for the cost of the two extensions I had made. However, the customer service rep. concluded that there was something "unique" about my truck (I removed a completely stock exhaust system and have made no other modifications to the truck). Weird - I have no explanation for why the kit did not fit well. For that matter, the local muffler shop that made the extensions backed up Flowmaster. They couldn't believe it either.

I look forward to your next post after the shop performs the fix. I am curious what their fix will be.

Dirk 1997 F150 4x4 5.4 S/C ORP + Flowmaster

 

DirkR
Well Dirk, I could not wait until this weekend to fix the knocking and banging on the new exhaust system. We got it on the lift and discovered that the left exhaust from the muffler was 4" short which allowed the pipe to hit the differential hub at every slight bump. Sure enough as you identified earlier in your post, a 4" extension was necessary to clear hub after it came over and down toward the rear. The right side did not require an extension. However we had to readjust the pipe because it was too close to the spring and was rubbing. A few little mods to get it right considering this was a custom fit. I'm glad I read your experience and want to let you know I appreciate your help. I took the truck out on the Cross Town expressway here in Tampa, the closest I could find to a test track. No rattles and nothing knocking only the deep mellow sound of Flowmaster. Later the shop did call Flowmaster and describe the problem. Hope they can engineer the fix. Again, thanks for all your input.
Ray Davis

 

Hi Ray,

Very interesting indeed... I wonder what Flowmaster will do with at least two calls now describing their system being too short on Ford trucks.

How does the performance feel to you? Does it feel like it has more power or torque? High end or low end gain? Also, if you track your mileage, I would be interested to know if you report any increase in MPG.

I just wish I knew someone here in San Diego who had chassis dyno. That way, I could have done true before and after tests.

The Force II kits sure do sound nice though!

Dirk 1997 F150 4x4 5.4 S/C ORP + Flowmaster

 

Hello Dirk,
After two tanks of gas, the miles per gal increased. We use our AC much more than any region in the U.S. here in Florida and may not get the best performance (MPG). However, prior to the Flowmaster and K&N filter I was getting an avg 15.7 MPG. Now I'M getting 18.8. Seems to have more zip at the low end getting away from the stand still. I'm a little quick on the take offs because of the nice sounds. High end, can't really tell but gets out on top real quick. Still trying to aliegn the pipes as they come out the rear. Just want everything neat. So, thats my un-qualified evaluation not knowing too much about performance or exhaust systems or cat backs.
Ray Davis


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99 F150XLT,SC,4.6,Auto, Short Bed, 3.55LS, Tow Pkg, Liner, Snap on Tonneau, Black/Silver Accent Flowmaster DOR with stainless tips, Westin Chrome nerf bars, K&N Air filter and more to come.

 

Hi Ray,

Glad to hear about the improvement. I do think those K&N's help too.

Also, I know what you mean about getting it all lined up just right. I fussed some with mine too.

This is going to be a short message as I am holding my newborn son (born 6/25) and typing one fingered.

Talk to you later...

Dirk

 

Congratulations Dirk to you and the family. I know the experience and joy of being a father. We have two grown boys and a lovely daughter, all in bussiness for themselves. For now you take care of the little guy. I'll keep in touch. Again, thanks for all your help on the exhaust system.
Ray Davis