Has anyone on done duals on a 4.9 six and what would it sound like? my exaust rotted off years ago and I'm getting tired of the sound of it with no exaust pipe past the catalytic converter. If I go to the trouble of putting pipes on it I think I'd like to try running duals. I think the actual plumbing would be fairly easy due to the split manifold set up on this engine with two pipes going into one.

 

Providing you have no emissions testing in your area or you'll need to put high flow cats on both sides to pass inspection. You'll lose some low end torque though. While it sounds like duals yield more power, they only do it at WOT. For normal driving the exhaust flow is so slow that the gases cool and become heavy. The engine literally has to push the exhaust out causing less air to be brought into the engine on the down stroke due to the back pressure at cam overlap. It's been my experience that there is no way to make a 4.9 straight six sound good. It's a great engine, no doubt, but it's not a hot rod.

 

Just a thought. The thing I really like is the torque level on this engine. I guess I'll just put a muffler on the back of my catalytic converter and quiet it down some.

 

When I ordered my 1990 F150, it was the XLT Lariet, SB/SWB with the 4.9, 5 speed w/handling package and 3:55 gears in the diff (4x2).......

Mine IIRR, had two converters on it, after the converters, I had a muffler shop drop the muffler and add 2-2" diameter tailpipes out the rear with chrome tips....oh, the concerns they had about loosing torque, the ecm, etc.....after a 1 hour call with the Ford dealer and them on the phone, all was good to go!

It sounded awesome........at tat time, the cats absorbed about 60% of the sound, so it really was quiet with a nice rumble...not loud, etc....no drone either and the truck ran fine...seem to gain just a bit on the rpms on the high side as far as ease of breathing goes....had that truck for 17 years like that....loved it and the new owner loved it as well.

 

No emission testing in my area. Someone with a little intelligence found out that the vehicles sitting idling at the testing center were producing more pollution than the testing was preventing, so they turned the test center into a body shop. I can trash the converters with no consequences. I have an old manual tube bender so I could build my own system.

 

we did that back in college on my roomates old at the time truck



sounded very very odd, and not in the a positive way

 

A couple of FYI's

1. Removing the cats will really not gain much power.
2. Even though you are exempt from inspections, you are not exempt from the requirement to have them- even US Fish & Game Wardens carry a manual that identifies each vehicle and the required smog equipment, illegal engines changes, etc with pics of how to ID.
3. Any law enforcement officer (including fish & game), EPA inspector, etc. can impound the vehicle and cite it as a gross polluter
4. Once cited, a judge will decide if the vehicle is to be scrapped or returned to the owner- and you do not have any opportunity to speak in court- just required to sit & listen.
5. If the vehicle is returned- guess what, now you have to repair and take the vehicle to a federal referee station for the rest of "its life" for a smog inspection & test.
6. An off road pipe or deleting your Cats is good for up to $25,000 via the federal courts

IMHO, it's not worth the risk versus the little gain.

Here's a link to a "Real Test" that verifies....on a 700+ hp engine......no gain or loss of with or without the cats!

http://www.kennebell.net/KBWebsite/C...aust_tests.pdf

 

If you are going to do duals, put a cheap high flow universal cat in each pipe.