After i did my 305 to 350 TPI swap and replaced the exhaust system with a hight flo cat and a magnaflow muffler someone said that i need to change the ECM when doing that? He said if i dont replace it i will have to go through another catylytic converter.

 

MAF car? You'll be OK. SD car, you should get a factory 350 chip.

 

What is MAF/SD? How do i know which one i have?

 

Does the mar have a mass air flow sensor (MAF)? If so, you're good to go. SD is speed density and uses a manifold absolute pressure (MAP) sensor to determine how much fuel to add but it needs to know cylinder size. That's why a chip change would be in order. If your car is an 86, it's MAF, unless someone went and changed it.

 

Ya i looked checked and it is an MAF car. so i dont need to change anything?

 

I called around and was told that i need a custom chip burned because of the 305 chip is still in but i have the 350 engine. It is still TPI. Does this sound right?

 

A MAF ecm doesn't need to know the engine size. If it were SD, it needs to know the engine size and would require a chip change. You have MAF, it needs nothing but if you would like to change to the appropriate 350 factory chip for you year car, go ahead.