Whats the benefit of running either of these over separate pipes? I hear a lot of talk about them being beneficial, but I don't understand why.

Chris

H pipes help with low end torque. X pipes with High end rev and power. Both help by balancing the exhaust pulse and help with scavenging. If you have room under neath put one in it will help. But here is the trick. You first have to find where they will do the best job. You paint the exhaust from front to back cheap .99 cent paint works. Run it up and the road a bit the engine should be at operating temp. Next see where the paint burned off where it stopped burning is where you want the H pipe or the exit ends of your X pipe. Now if you have cats put the entrance of the X pipe at the exit of the cat and the exit where it stopped burning. That is if your cats are where they should be up close to the engine. Hope this helps

I'm interested in this too as I'm running separate pipes and separate cats. What % power am I losing due to not having H or X pipes?

twice the muffler area for the exhaust pulse to flow through

not only they help the engine performance, they also generally make the exhaust sounds better as well.

H pipes help with low end torque. X pipes with High end rev and power. Both help by balancing the exhaust pulse and help with scavenging. If you have room under neath put one in it will help. But here is the trick. You first have to find where they will do the best job. You paint the exhaust from front to back cheap .99 cent paint works. Run it up and the road a bit the engine should be at operating temp. Next see where the paint burned off where it stopped burning is where you want the H pipe or the exit ends of your X pipe. Now if you have cats put the entrance of the X pipe at the exit of the cat and the exit where it stopped burning. That is if your cats are where they should be up close to the engine. Hope this helps

I googled "exhaust scavenging" thats pretty interesting stuff! Thanks for the info... makes a lot more sense now.

I'm thinking about building an exhaust for my DD f150, but I know if I do I will go overboard on it :laughing: I should probably just replace the muffler and call it quits. These trucks have 4 cats anyway, I doubt anything will even do much good at all :shaking:

Chris

Actually you could do a cat back exhaust and that would help quite a bit. What I did on my 85 bronco it had 4 cats. I went to a true dual with high flow cats and mufflers I even did the air injection to both sides. worked great. I was all 2.5 inch tubing.

Now on my DD/tow rig I did some thing different to save money. The stock cat had clogged. Then came apart clogging the flow master. Well a new stock cat is 300.00 because the way the pipes come into it. So I left the stock cat where is was finished cleaning it out. Coming out of it is 3 inch so I put a high flow Magnaflow cat 3 in 3 out then an Hooker Aero chamber muffler 3in 3 out that goes into the stock 2.25 dual exits. Sounds good and I gained some seat of the pants power.
The front gutted cat acts as a resonator. I went ahead and did the paint trick and the paint burned of all the way to the muffler and a little into it which means my exhaust velocity is plenty high and scavenging great. Total cost for parts 195.00 labor I did.