how hard is it to hook the stock y pipe back up after a set of thorley lt headers? my headers should be here about the middle of this week. what kind of mufflers should i run? i was thinking about single chamber flows. thanks for any help.

 

you have to chop the short section in front of the cats somone on here has a really good write up with pics about it,
I just welded up a new y from mandrel u bends. If you can find someone to do it or have access to a shop thats the route I would go. I picked up more from just the y pipe with no cats than from the headers.

Just a thought hope this helps

 

Wouldn't you have put them on at the same time? (headers/y-pipe) How do you know you gained more from the y-pipe than from the headers?

 

this was of course from my very accurate butt dyno
I felt more of a difference

I did the y pipe first just had em weld it directly onto existing pipe coming down from manifolds, that way when I did the headers it saved me some work and I eye balled it cut the pipe put the headers on and had to finess the existing pipe into them (heating and bending with tow straps) bolt the flanges to the headers then jam the pipe in there and weld viola

Getting rid of that damn stock y pipe and cats is cheap and realitvley easy plus it nets around 25 rwhp from things Ive seen on other trucks.

 

99stepside, where are you getting your thorleys from and which set are you getting? i want the ceramic coated but they still run close to $700 for the set. i wonder if it would be cheaper to buy the cheapest set and then get them coated afterwards.

02sierra, i have a dual in/out magnaflow on my truck and was wondering if i were to get a custom piping w/ high flow cats (i have emissions to worry about) from the headers to the muffler would i still net about 25rwhp? because 25rwhp sounds really nice.

 

Would a flowmaster Y pipe be similar to what you have? I was thinking about doing this till I find some LT's I can afford for a 4wd

 

yes I used a flowmaster y, just buy some 2.5" mandrel u bends from jegs or someone only need 2 and take it to a muffler shop tell them what you want. If you live in a city you will probably have to find a shop in the country to do it.

to those who are worried about emmisions, I have one question

in all the inspections you have ever had has anyone actually looked under the vehicle at the full exhaust. I never have thats why I dont worry about it, plus Im in NC and the good ole boy network is alive and strong

 

If anyone decides to go this route Ive got a 2.5" u bend left over and Ill ship it to you for 10 bucks, jegs charges 15+shipping

 

Here in New Jersey they have a mirror on a pole that they stick under the vehicle to check if the cats are there...they could be empty cats, but they still have to be there. If it's a 96 and up, it just needs to pass the OBDII plug in, older vehicles have to pass the sniffer