I am thinking about doing and exhaust on my 7.4 L (454). I have been back and forth on whether or not to leave my cats in or to take them out and put dummy O2 sensors in. Also i am worried about the sound and what muffler to put on. Any suggestions?

What kind of vehicle? Do you require emissions testing where you live?

Its a 98 gmc truck and no there is no emissions testing here.

you can take the cats off and use the dummy sensors for the rear o2'* but the better thing to do is get a tune where they are tuned out. sound is subjective it depends what you like. i had a 89 350 i took the cat off of and ran just a summit muffler i think it sounded good, fairly mild at idle and semi quiet inside but if you get on it it was reasonably loud.

Where would i get the tuner?

You could either send in your PCM to a tuner shop to have those things turned off, or you can pony up the $500 for your own tuner and tune it out yourself. Downside to sending your PCM in is, you lose your PCM for about a week or so, and it runs you about $100 or so to have it done.

places like blackbear have a deposit you can do and they will send you one you send them yours later. if i was going to do that i would have them turn off the evap and security to prevent future common issues

If I were to buy a tuner what one would i get and where? Also is there a website or a phone number for blackbear?

HPTuners.com >> Performance At Your Fingertips


http://www.blackbearperformance.com/


GIYF

Given that catalytic converters are a federal requirement if equipped from the factory, and the fines are quite annoying when you are caught without them, and there is a bounty for ratting people out that don't have them, I am just going to have to suggest some nice high flow units.