So I'm going to buy them tomorrow and put them on later in the day. But I have a question Should I buy 2 and weld them right after the headers. Or save myself some money and just buy 1 and put it in right before the Cat? Thanks in advance. And o ya just making sure the stock exhaust piping on an 87 350 is 2.5 dia right? Im to lazy to go out and check

 

Depends. If you're running EFI, putting the cutouts right at the collectors risks mixing fresh air with the exchaust, making the O2 sensors read inaccurately. Been a while since I've been under a 3rd gen F-body, but if you have the room to put them at the end of the straight sections of the Y (before the two pipes curve), that would be better. Ideally you're going to want at 12" or so of exhaust pipe in front of the cutout. Other wise, save the money and do just one.

If you're running a carb on that engine, without 02 sensors, by all means, do it right at the collector.

 

I have one after each header collector on my car and it sounds AWESOME when opened up. Zero isseues with the 02's. Just be prepared for lots of noise

 

Thats what Im lookin foward to! You think it would be as loud with only one before the cat or should I just go for 2?

 

The loudness should be the same, or nearly the same. The sound will be considerably different, just like the sound on a true dual system is considerably different than exhausts with a Y-pipe.

 

Ya im just going to go for 1 before the cat. I think it will be to hard to put 2 on with the stock Y and shorty headers.

 

If your stock y is like my buddy's 87 Trans Am, I don't even see how you con imagine to put two cutouts on it.

 

Just be careful when welding near electronic components - like within the engine bay.