I gotta kinda agree with InnerCity here, why spend the cash on a high flow cat just to run it into one of the most restrictive, chambered mufflers on the market???

 

did the hi-flow cat effect your high end torque?

 

There is no y pipe on my truck. The 2 pipes come from the headers and go right into the cat. The pipes are 2" that go into the cat. The cat then has an outlet of 2.5". I'm having trouble finding a hi-flow cat that has the dual 2" in and single 2.5" out. I found this http://www.autopartswarehouse.com/sk...gs+Best+Seller but not sure if it is the right part. It doesn't say what size it is. Can anyone send me a link to the right part I need? I'm trying not to spend too much money

 

The Magnaflow direct fit will do the job. I got mine here.

 

the irony: Flowmaster = one of the most restrictive.

 

There may be power gains from altering the cat/muffler/pipe diameter but you should have a very clear understanding of what "power" really means to you (the driver) and to the guy selling you the exhaust parts.

Changes in the exhaust alone are not going to significantly alter the amount of power your engine produces. By "power" we mean torque, which is what we care about.

It may move the power-band higher or lower in the RPM range, however.

I say we care about torque because it is the main factor in drive-ability around town and even at highway speeds since there is no true close-ratio transmissions anymore in the world. EVery vehicle today is built to run at relatively low RPM at any speed that won't get your vehicle impounded.

Torque is the only thing that can actually be measured; a dyno cannot measure horesepower but must derive a HP number from the torque value using a mathematical formula, torque is the only thing a dyno actually has the ability to measure.

Because Torque x RPM * is horsepower, the same torque output of the engine but moved by a less restrictive exhaust to a higher RPM gives a bigger HP number.

So, the guy selling the less restrictive than stock exhaust can ALWAYS say it "increases Horsepower". It *might* increase torque a small amount as well **, but that's not guaranteed, and usually requires a corresponding change in the intake system from stock.

* It's actually HP = [torque x RPM] divided by 5252. Because you do the torque x RPM multiplication first, and because the next step involves a constant, it's easy to see that moving just the RPM higher gives a bigger number for HP.

** There are certain points where the Volumetric Efficiency of the engine is highest. If by some chance the RPM that the less restrictive exhaust moves your peak torque to also happens to be an RPM with improved VE, you can have an improvement in torque there as well.

The best way to improve power is to choose cam timing for the RPM range you want, and build the exhaust to take advantage of that RPM range. The next best way is to reduce restriction in the intake (air filter, clean air box, etc) to go along with a less restrictive exhaust. The ideal is to improve intake, timing, and exhaust together.

Dual exhaust tends to narrow the torque curve with a higher peak, while single or dual/x-pipe tends to broaden the torque curve with a lower peak.

 

i'm looking at getting a MAGNAFLOW 23285 hi-flow cat (http://www.ebay.com/itm/170637143204...S:1123&vxp=mtr) and a 94-01 Dodge Ram MagnaFlow Dual Exhaust Mandrel Bent (http://www.ebay.com/itm/94-01-Dodge-...04124386023486)

does this seem like a good combination?? can anybody tell me what effect it will have on my engine, if i will gain a little torque or lose any???

 

I have that cat and the pipes that came with it a rotted through pretty bad and have splits and multiple holes...I'm likely going to replace the whole setup since I cant even seem to be able to find just the mandrel bent pipes to go between my headers and cat. Plus I'm not sure of the state of the cats performance at this point being it was there when I bought the truck.

 

how long did u have it before it started to rot?

 

I dont know... Like I said it was there when I bought the truck. I noticed a small hole about 6,000 miles ago...now the pipes a goner. Its held together with jbweld putty right now.