As the title says I'm wondering about that because I'm about to have some exhaust fabrication done. It's a minor consideration for me but I am curious anyways.

Just to share; My goal is to create a budget yet effective free flowing exhaust for my 87 NA. After doing a bit of reading here and elsewhere I decided to buy a mandrel bend for the downpipe from exhaust manifold 2.5 in heading into a long dynomax racing bullet (cats are being deleted), then into the Y-pipe and out into a pair of Walker Ultra Flo SS's 2in mufflers. 2 in mandrel bends also purchased for this section.

I plan to use an airpump mod for 6PI.

I was planning to replace the Y-pipe with 2.5in into two 2in pipes but now I'm wondering if that would make any performance difference. I've been assuming that the Y-pipe intersection doesn't involve crush bending so if it does then I should go with new pipe but if the stock exhaust is mandrel bent then I might leave that section alone.

 

If you don't have cats and have at least the same diameter pipe as the stock exhaust, I don't see you NOT getting some added performance.

 

Since there seemed to be some confusion just disregard everything in my opening post.

My only question is: Did the original OEM 87 NA exhaust piping from the factory use mandrel bends or are they crush bends.

 

Considering the stock exhaust is comprised entirely of flanges, catalytic converters, a crazy transition through the split, and mufflers...I would say the exhaust doesn't have any bent tubing at all.