2000F15046

the plan is to run 3 inch pipe for true duals out the rear with flow tech red hots and do a rear cat delete.

what would be the pros and cons of using glasspacks and doing the rear cat delete...i have used the search on many f150 forums and havent found out exactly what i wanted to see. will it be better to use 2.5 inch pipe and big tips or 3 inch and big tips. walker exhaust makes smooth bend truck pipes and i can get them and a 10 foot peice of straight pipe for under 100 bucks. i am open to any opinions....with 3 inch will i have enough back pressure if i leave the 2 front cats and use glasspacks?

thanks for the info..


and yes i am a new user but i am not new to any of the f150 forum sites, like i said above i have searched over all of the forums but theres nothing i seen that will help me besides some of the infor about the rear cat delete...i will have questions about that later in time though.

GATORB8

You don't want backpressure, you want the increased velocity from the smaller tubing allowing the exhaust to scavenge. 2 1/4" should do you (i'm assuming you've got the 220HP 4.6), which is Flowmaster's general recommendation for duals up to 325 HP.

rc_ayers

yeah if you want your torque to drop than you dont want back pressure with these duel over head cam motors they need their back pressure. when i pulled my muffler off i felt that my low end had dropped. but rear cat delete with glass packs or dynaotech billets should be just right and still have good sound

2000F15046

ok well i dont want any o2 simulator BS so that is out of the question(not that you two have mentioned it yet) but should i keep the rear o2's where they are or move them to behind the front cats? i want a legal look....besides the glasspacks as the cops around here only care about noise, so if i dont hold my foot to the floor going by they wont say anything. i have the pipe to delete the rear cats, just would like a bit of detail. i dont wanna cheat with the spark plug non foulers either as i can buy o2 bungs and have a welder to weld them onto pipe with.

will my trucks fuel economy improve under same driving conditions if i remove the rear cats?

sorry if it sounds like im all over the map here but i am trying to use this thread to get answers for two questions.

thanks.

rc_ayers

ok so you do want to do a rear cat delete as far as fuel economy goes idk i havent talked to a lot of people about that. i also would leave the o2's where they are but most people i talk to say that they dont have problems withe the o2's

Landman88

I had the shop remove the rear cats when installing my true dual glasspacks. Go with the 2.25 inch pipe, and all you gotta do is re-intall the rear o2 sensors back into the pipe and you will be good to go. I haven't had any problems, check engine lights, or anything.

2000F15046

well would it be bad if i ran 3 inch pipe from the muffler back? or from the cat back? what would be the pros/cons. and did you lose hp or gain any fuel economy by removing the rear cats?

GATORB8

Single 3" should be fine, here's FM's chart:
Tubing Size
Dual Exhaust
2.00”
up to 200 HP
2.25”
up to 325 HP
2.50”
up to 500 HP
3.00”
up to 600 HP

Single Exhaust
2.00”
up to 100 HP
2.25”
up to 160 HP
2.50”
up to 250 HP
3.00”
up to 300 HP

formula150nh

you should post a video when its done

nunchakyo

yeah post a video. I want to do the same thing. Im not sure if i want a cat delete, some people say deleting all 4 cats is just an annoying sounding, but i heard deleting only the back two gives it a decent sound. I would stick with 2.25 or maybe 2.50. 3inch is pretty big.