I recently installed 20" rims on my F150. I have a XLT 2004 supercrew with a 4.6L engine, automatic. I took it to the dealer to reprogram the tire size and I was told that their current program did not support tires of this size. Has anyone else had this issue?

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I am also considering installing an exhaust, intake and programmer to this truck. Will I even notice the difference on the 4.6L? Most of my driving is towing a bass boat. It tows fine now. Has plently of power. I only notice the weight in hilly areas and some over-passes. I am looking for some power gain and maybe a little improvement in mileage.

thanks,

Greg

 

Sock, first of all, great looking truck! What kind of rims are those? Second, where is that picture taken? It looks great too!

As far as mods-the only mod I've done so far (mostly because I couldn't stand how quiet my truck was) was install a Flowmaster Original 40 muffler. I dispensed with piping all together and dumped it under the bed before the rear axle. While this is perfect volume for me, it's too loud for most people.
ANYWAYS, as far as performance, I have detected a noticeable increase in throttle response and less hesitation at higher RPMs. This will no doubt improve more as my engine breaks in (I only have 500 miles on her ). Magnaflow or Gibson makes systems that are quieter but improve performance significantly. Also, my MPG is showing slight improvement-again, once the engine breaks in that will become more significant. It is probably important to note I also reduced backpressure by dispensing with over-the-axle piping, which is often crimped and restrictive.

My next mod will be an air intake of some sort - right now I am torn between an AEM (see ChrisAdams' post, he has a prototype on his truck, since the 4.6L version isn't out yet), a True Flow system that retains the stock airbox, or the Airaid MIT, which replaces the intake tube from the airbox to the throttle body. Everyone who has one of these systems reports a decent gain of some kind.

 

When I had 20" wheels put on my truck, I went ahead and got a Superchips Microtuner so I could reprogram the speedometer as well. I also have a MAC Air Intake, Flowmaster 40 Series exhaust, and other exterior mods. The chip on 93-tune makes a dramatic performance improvement. Those long hills where your 4.6 usually lugs or has to downshift to keep up with traffic will be taken with ease - thats the best part. I haven't measured 0-60 times or anything like that, but I can tell you that I can smoke a 2002 Ram Quad Cab 5.9 V8. If you have any other questions, be sure to ask!

 

Thanks for the comments fellas!

The rims are American Racing Matrix with Goodyear Eagles.

I took the picture at Fayette Lake, it is southwest of Houston.

I think I am going to try an exhaust and programmer first.

Greg

 

Good deal man. What gearing do you have in your truck? Lowering the ratio (numerically higher) will give you better power by moving your truck easier. Exhaust sounds great on the 4.6L, believe me . You might want an air intake before a chip, because you might as well take advantage of the fact that the exhaust can move more air out, so you should put more air in! (Should be cheaper than a chip too, and it may do the trick with the exhaust!)