Can taking off the converters damage your engine? -Vince

 

It's illegal under federal law and most likely in your state as well. More importantly and it'll screw up the OBD-II to a fare thee well. Cats cost at most 10HP at top end and can actually add mid-range torque. High flow cats are a good idea but it's also illegal to remove an undamaged cat at under 50K miles. Better to be a good citizen and live with it.

 

Wow was that the "Cat police?"

 

I was wondering because i have a '91 F-150 (95,000 mi on the truck with a new 5.0L engine from the dealer 8,000 mi ago) It has the original converters on it. They need to be replaced and i was looking at the high flow converters too. I have straight pipes (with glass pack) on my truck right now.

 

With a '91 you don't have OBD-II to deal with just the EEC-IV processor. It is possible, but still illegal, to remove the cats. With over 50K on the truck you can replace them with high flow larger diameter cats and still stay smog-legal and gain top end HP and keep your mid-range. Your EFI system is speed-density not mass air so you can't do a whole lot with the engine, but a set of high flow cats and 2.5" cat-backs should work very nicely without confusing the S-D control

 

Thanks, im probably going to go with the high flow converters. -Vince