Hello. I have a 98 F-150 4x4 with the 4.6 litre. It has dual exhaust, but the pipes are quite small in diameter, I'd say about an inch and 5/8. I'd like to install new larger pipes, like say 2 inch or 2 and 1/4 inch, but am not sure if doing so will harm my engine or performance due to less backpressure. (I've heard in the past that engines need some backpressure to operate properly) Does anyone know if going to larger pipes with Dual Exhaust with the 4.6 litre is a wise thing to do or not? If so, what would be the max diameter piping that I could install?

 

There comes a point where yes, too big is just that = no backpressure. You should have like 2- 2.5" at most, or a single 3", I'd maybe say 2-2.25" is the normal.

 

I had a 98 F-150 4.6L. I wish I would have kept it. Best truck I've ever had.. I still see it drving around town at times..

At about 35k miles I ripped off the factory piping from the cat. back and had a shop put on a 2.25" dual rear exit system on. I also had long 3" tips to finish it. No muffler either. It is the best sounding setup you can do on a 4.6 hands down. Its not that loud, but nice and throaty when you step on it. Never once got stopped and our area can be strict on that. With a 5.4 its too loud, but the 4.6L is perfect. Performance and gas mileage went up as well. Best mod I ever did to that truck. Sold the truck with 90K and never had a single problem.

 

I have an 02 4.6 and am running 2.5inch pipes. i put on tru duals from the cats back and it sounds great just not loud. hope this helps

 

2" - 2.25" would be perfect.

 

I have 2.25 inch piping...my exhaust guy said I could have gone with 2.5 but I wanted to go with a little more backpressure and I am extremely happy with the result. I do have 3" tips...but those are just for looks