Does anyone make a 3.5" dual exhaust for the RX-8? That means 3.5" coming from the cats/ midpipe. Or would I have to make something custom? Thanks.

thewird

 

custom

 

3.5" would be Ginormous! I did 3" and most think that is huge.

 

that would be a monster, especially dual!

 

This would be for a turbo application for those that think its too big. The idea is to run 3.5" main pipe that splits into dual 2.5"-3" mufflers (I'm still trying to find information on proper flow diameters to match the 3.5"). This will reduce backpressure for top-end and EGT's. As well as improve turbo response.

I'm planning to run a 35R-40R turbo (undecided) with my own custom tubular manifold.

On my RX-7 with a 500R-SP (67mm compressor, 0.84 divided hotside) with a full 3" straight-through exhaust all the way to the back, I get around 3-4 PSi of backpressure at 16 pounds of boost and 5-7 PSi of backpressure at 20 pounds of boost. My old Racing Beat dual-tip used to provide over 10 PSi of back-pressure at 16 pounds of boost even though it was 3". I'm going to be upgrading my RX-7 exhaust to 3.5" this winter as well.

thewird

 

Did you check the flange where the racing beat bolted to the midpipe? I had an aftermarket midpipe and a RB exhaust but both were designed to bolt to the stock components. I had the flanges for each cut off and replaced with a slip fit. It's not the most brilliant of solutions, but my point was even 3" exhausts may not be fully 3".

 

The Racing Beat I was referring to was the one for the RX-7. The piping is in fact 3" as the 3rd gen RX-7 comes with 3" exhaust from the factory it bolts up stock. I already had complete straight-through when I did the test so all the restriction was coming from the muffler itself.

thewird

 

Dual 2.5" equate to a single 3.5".