Hey guys I was just wondering what yall thought about running straight pipes on the HD. I want big deep sound and I think this is about the only way to achieve it. If I want to I can always put the muffler back on fairly easy. Any suggestions or opinions?

 

Will sound cool. Just not very practical for my application. May result in lowered bottom-ended torque??? Don't know exactly how restrictive our mufflers are as is. Are you gonna keep the cats on? Are you gonna do without the Y-pipe? What are you planning?

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Stay Out Of My Taildust

2000 Black Harley Davidson F-150
5.4 Liter v-8
K&N Air filter
20" Polished Aluminum Wheels
275/45/20 Goodyear GSII's
Billet Front Grille
Front Valence W/ driving lights and Billet Insert
3.55 LS Rear End
Leather Interior
6 Disk CD Changer
Sliding Rear Window
Heated Seats
Hidden Hitch
Orange Pinstriping
Lund Front Blackouts
GTE Rear Blackouts
Lowered 1" Front & Rear
Block heater
McGard Wheel Locks

 

I was gonna keep the cats on and replace the muffler with a Y pipe. But I don't want to lose any low-end torque, I was actually hoping I would gain a little. What do ya think?

 

Depending on how restrictive our muffler is versus the cats, the lower back pressure could result in lower end power loss. Check out the exhaust section, I've seen a couple guys talking about his.

Also, the Y-pipe is the pipe coming from both exhaust manifolds adn contains a CAT on either side. Then converges into a single pipe into the muffler, then out to a dual outlet. (If I remember correctly). You have 2 options for keeping the cats and running 2 straight pipes. Depending on your local laws, one is deffinately illegal, one is only legal in states that don't require mufflers.

First, you can cut into the y-pipe just after the Cats, and splice your straight pipes straight back from there. This method is illegal. It's prohibited by federal law to alter the section of exhaust that houses the cats (namely, the y pipe). Thus "true duals" are illegal.

Now the second way is to attach a splitter after the y-pipe, and run your duals out from there. This is legal in areas that don't require mufflers, but your basicaly not doing much. The point of highest constriction is the Y-pipe junction, which you're not supposed to touch.

It's like having a 4 lane highway cut down to 2 lanes, then open up to 6 lanes. The point of constriction is where it goes to 2 lanes (Y-Pipe). Even though it opens up to 6 six lanes down the road (open pipes), no more cars are going to be able to get through the 2 lane bottleneck.

Am I oversimplifing this? If I am I'm sorry, I'm a foreman who has to give directions to idiots all day, so you can understand.

So, what's the solution? Screw the cats and mufflers, slap on a set of headers feeding into true 3" duals out the *** end!!!!!!

Mike

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Stay Out Of My Taildust

2000 Black Harley Davidson F-150
5.4 Liter v-8
K&N Air filter
20" Polished Aluminum Wheels
275/45/20 Goodyear GSII's
Billet Front Grille
Front Valence W/ driving lights and Billet Insert
3.55 LS Rear End
Leather Interior
6 Disk CD Changer
Sliding Rear Window
Heated Seats
Hidden Hitch
Orange Pinstriping
Lund Front Blackouts
GTE Rear Blackouts
Lowered 1" Front & Rear
Block heater
McGard Wheel Locks

[This message has been edited by BlownHarleyFord (edited 04-12-2001).]

 

Good explanation, Mike, and YES, you will definitely lose low end power if you take all the restriction out.

Maybe agrv8vn will jump in here, he has done a lot of experimenting with his exhaust and bet he's got a solution.

Don

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2000 F150 Harley-Davidson: Superchip, K&N FIPK
Hard Tonneau, Hidden Hitch, 2-Meter Rig (KG0UK)
'99 FLHRCI, '95 XLH

 

You mean straight pipes off the exhaust manifolds? or after the Y pipe?

Removing your muffler and running large straight pipes into even larger tips will certainly raise the sound level...probably to headache levels.

Why not get a nice aftermarket performance muffler. Bullit makes mufflers that are basically Straight pipes . Great Grumble...even more than the flowmasters..and sounds wonderful.

dont remove your cats or Y pipe just to run straight pipes off your existing manifolds...its a waste of time and will just make you slower. Even buying aftermarket headers/system will slow you down off the line. Our trucks dont have the cam design or valve lift/duration to fully utilize such a free flowing exhaust. Sure it will make 10hp or so. but thats at MAX RPM....and it will most certainly show up as a loss in Torque and HP at the low to mid range..where 99% of your driving is done.

I know you want to make the truck faster...but that is not the way to go about doing it. Put NOS on it or buy a supercharger ...something that will add some grunt down low.