I've got an 03 Scab short box with the 4.6. There are two exhaust leaks at the two joints between the muffler and cat pipe. Instead of taking it to an exhaust shop to have this pipe replaced, it seems like a great time for a catback kit. I'm looking at the Gibson 9504 or the Flowmaster 17222. The instructions for the Gibson state that 4wd trucks must lose the spare tire. Why is the spare tire location on a 4wd any different than a 2wd? Is it because of a taller profile tire? It's just a 16" rim. The Flowmaster kit makes no reference to the spare tire at all. I'd like to get the Gibson kit, but I don't want to lose the spare. I searched and found one post where people said "it should be fine." I'm wondering if there are a few people with firsthand experience with these systems and fitment around the spare tire. As far as fixing my exhaust leaks, it sounds like you cut the pipe off right in front of the factory alignment key with the Gibson, so that should cover me there, and the Flowmaster makes it sound like it connects at the factory alignment key, so that should work as well.

 

If i were in your position I would buy the muffler of my choice, take it to an exhaust shop, and tell them what to do. Just bypass this whole problem. The only reason i can think of for the Gibson instructions saying that is because 4x4s come with bigger tires.

 

Some folks have interference issues; some don't - to the point of having the spare melting from proximity.

You may be able to shift yer spare laterally to allow adequate clearance, but it's entirely yer responsibility - Gibson's CYA boilerplate (see below) makes it so.

This is an aluminized system - it will rust (and quickly) if y'all are in the Rust belt.

Be advised as well (from Gibson):

"On some vehicles the spare tire may need to be relocated or removed. Works with most bumpers, roll pan and trailer hitches. Not recommended for towing, because carbon monoxide may be drawn into the interior rear of a vehicle when an exhaust pipe directly exits to the rear of the vehicle. Exhaust can be louder under towing conditions. "

The single-side exit systems do not have the above issues.

Maggies sound better than Gibson, & don't have internal restrictive baffles that tend to break loose & rattle. And Flows are pure crappa-frappachino

MGD

 

The advice of buying a new muffler and having a shop weld it in and replace the intermediate pipe sounds like a good plan. I'll probably just do that and save myself some money and potential headache.

 

This should help:

https://www.f150online.com/forums/4007591-post14.html

MGD

 

Magnapacks or Bullets.

 

OP - if you are really serious about uncorking yer exhaust, while the muffler shop is under there, have them install the following (procedure is in the text):

http://www.troyerperformance.com/cgi...atalogno=10778

The factory 'Y' on yer model year truck is basically a butt-plug; hugely restrictive.

MGD

 

I'm not really concerned about performance. I just want a little better sound. This is just my putts around truck. I'm more annoyed by the exhaust leak than anything and the fact that it idles a little rough from time to time, presumably from the leak.

 

Fair enough, but a simple low-cost alteration like that to fix a glaring OEM deficiency, in the name of increased efficiency, given the fellers will be under the truck anyway, is simple prudence.

But - yer call.

MGD