I have a 2003 Dodge Ram Hemi with a K&N cold-air, hypertech programmer, taylor thundervolt shortywires, no cat with a 3 inch pipe form the y-pipe to a dynomax bullit. But I was wondering if puting back the cat would be better or a hi flo cat back on. Plus the check engine light is on cause of that. Is this slowing me down? Does the engine needsome back pressure? So many questions. Just need some help. Thanx

 

the muffler is giving ya back pressure and until you get some serious build up... it wont be a huge benefit to run catless imho. still id run a highflow if ya have the funds so that if you do add a nice cam or what not your good to go.

 

I run catless, and there is a very easy fix to your check engine light problem. Buy2 O2 sensor bung and get a piece of steel piping at least 4 incheslong and the same outside diameter as the O2 bung. Cut the pipe into 2 2 inch pieces, drill a 3/8s hole into the Y-pipe one after each collector, weld the a bung the each end of the pipe, weld the other end of the pipe centered over the 3/8's hole u drilled screw the sensor and and no more check engine light. Thats what i ended up having to do on my off-road Y-pipe and it works great... btw dont try to use spark plug non-foulers as spacers they dont work with our O2's.

 

My muffler is a straight through design and has a 3 inch inlet/outlet so I dont think my muffler is giving me back pressure. And its better to run catlesswhen i runbigger mods then??

 

If you run catless you should see better gains... not by much but it will be better. As far as your muffler it has to be giving you some kind of back pressure because in the process of muffling and manipulating the sound of your exhaust it will create some restriction which makes back pressure.