Replaced the muffler on my '05 F-150 with a 4' piece of pipe, (still exits behind wheel). Sounds great & is not real loud. The four cats muffle quite a lot. It isn't objectionable cruising & doesn't "rack" back.

 

4 cats :eek. I thought two was bad. I never new they put more than two on any vehicle. I haven't ran a cat for 5 years on my "90 bronco and has passed emmisions test every year not visual but sniffer passed - I so believe they are a scam. I'll never go back to them.

 

Think mustangs ran 6 for awhile there.

 

I read where the front one on each side is a "preheater", but any way you look at it, there are four of the darn things. Sounds ok, I guess they're my mufflers! Also the truck feels like it has a little more torque, pulls several of the hills better, I noticed it stays in OD longer before shifting down.

 

I cut off my muffler on my '86, it sounded real deep and it wasnt really loud...but i didnt notice a power increase until i dumped the cats and went with straight pipes and glasspacks