since i nstalled my highflow cat , it feels to me i lost power, im wondering if i have too much flow ,not enough backflow, high flow cat to a single chamber muffler , anyone else feel as if they lost power with a cat. maybe im just imagine that im losing it lol.

 

I honestly don't feel like I lost power but I don't feel like I gained much either. I had the cat put on then came home and put a new front 02 sensor on. After that I couldn't tell if I gained a slight bit of power or not but it wasn't much if any. It did get a bit louder though or so it seemed. It might have helped slightly power wise but not a ton. I don't think I really lost any though. If I did I couldn't really tell it. It's soo hard to judge if you get power or lose it with these mods though. I could lose a hp or two or gain that amount and probably never know it either way.

 

What size pipes you running?

 

That's a good point. I have a 2.5" pipe from the cat to the muffler and then 2.25" pipes coming out of the muffler exiting to each side behind the tires.

 

the power on my truck went up when i put in my magnaflow cat. have you checked the O2 sensors?

 

Funny, because my truck feels like it lost power after installing the Magnaflow converter and Flowmaster muffler. Although I'm not sure if it actually 'lost power'- but I've noticed that my transmission doesn't kick-down like it used to. When I'd stomp on it between 35-40 mph the tranny used to kick-down and throw me back a bit, but now it just accelerates without the kick-down; so to me, it feels like I lost something.

 

i dont have a magnflow, but i have the gutted cat, to a glasspack. mine got a heck of alot louder and i couldnt tell the power cause my o2 sensor, thats what i would check

 

Both O2 sensors were replaced when the new cat & muffler were installed.

 

years ago some Dakota owners got together for a rear wheel dyno day
and if memory serves me right they found that substituting a straight pipe for the factory catalytic converter gained 4 rear wheel hp, but I don't remember if that was on a 5.2 or a 5.9 V8

Kenne Bell says posts on their website that on a 1998 Magnum 5.9V8 Ram,
taking off the factory exhaust just behind the catalytic converter
gained 16 rear wheel hp

my own tests on a 1995 Magnum 5.9 V8 Ram showed that the stock factory exhaust had 7 psi of back pressure at full throttle and 4000 rpm at 400 feet above sea level, measured at the top of the EGR tube on the 'back pressure sensing' port of the EGR modulating valve

 

It's very possible you lost some power and/or torque in the low range. In many motorcycles, including my R1, they put a butterfly valve in the exhaust. It's partially closed at low rpm to increase torque, and opens fully at high rpm. Variable valve systems do the same thing. They limit exhaust flow at low rpm for better torque.

I remember we took the cat off a Miata and put in a 2.5" complete exhaust. It lost a lot of power down low, but revved and ran better at 5k+.

Since then, I don't personally like open exhausts except in turbo systems. Hell, 99% of the driving most of us do is below 3k anyways.