Hi to all,
I'm new here.

I kept my grandpa's truck its a Mexican truck F-250, engine 351W EFI manual trans, its a unique edition called "fighter" it used to have the one pipes under each door (soon I will upload a photo when still has them).

Well that's was only a description, I repaired the engine last year, its in good shape now, the only thing is that its burn's a lot of gas. I put 2.5'' dual pipes, I'm not installed a catalytic converter neither oxygen sensor, I need some help regarding this, i don't know if I should put the catalytic converter, and if the oxygen sensor need to be installed before or after the catalytic converter(I only find one oxygen sensor connection), the catalytic converter connection has two wires.
Also I want to install a Airaid Throttle body spacer & air intake system, did you think this would help?

This is all for now, I want to start with this things first, will appreciate if you can help.

I upload a recent picture of my truck if you want to take a look, working on more pictures.

Thanks...

 

Don't get the TB spacer, zero gain in HP and MPG.

As for the intake, everyone will tell you they don't do zip. I bought one shortly after I bought my truck and would say that there was a mild HP increase, but from what I've read, if the intake is pulling in warmer air, due to an open filter under the hood, your mileage will decrease. most people say to get the intake tube from a 460 or 300 and install it.

 

Also, when you say bad mileage, how bad is bad?

As for the O2 sensor, it goes before the cat, so don't worry about putting one on.

 

If you don't have the oxygen sensor installed the computer will run in open loop and will not be able to get readings so it will get worse fuel economy.

Don't waste your money on chips, throttle body spacers, or cold air intakes. They are junk.

 

I guess I should correct myself here, when I said don't worry about putting one on, I meant the cat, the O2 sensor is definitely a good idea.

 

Thanks all for your comments it really helps, I will start planning on the oxygen sensor, then I will run some tests with the computer
Hope I can get some fuel economy.

Thanks again.

 

Yes that o2 sensor will help alot