These oval elbows were a problem. We liked the look of them, and had spent ninety dollars a piece to own them. Unfortunately, we also ended up wanting to mount our custom muffler at a tilted angle for beneficial packaging reasons.
This meant that typical ninety degree oval outlets on the muffler would have the exits of these elbows poking into the trunk of the car. Trying to get a custom angle on the outlets would have been possible, but if our educated guess for the measurement of that angle turned out to need tweaking it would add considerable fab time what with the funny oval pie-cuts required to do the job.
It was at that point, in the interests of simplicity, Tim drew up this wacky thing:
The idea was that he’d rather make his own 2 1/4 to 3 inch oval transitions than try to wrestle with a tilted oval outlet. In this scenario we would pinch the outlet side of our custom muffler to accommodate for Tim’s round-to-oval adapters. This gave us all round inlet and outlet flanges on the muffler so we would be free to set the angle of our exhaust tips by rotating our elbows around the circular muffler exits.
We showed this drawing to Ron, our contact for custom products at SpinTech, to see if it was ridiculous or not.
Ron surprised us when he showed a lot of enthusiasm for the drawing. He interpreted it as an aggressive, un-crossed two chamber muffler design. It would essentially be two separate mufflers in one body, with no gas exchange between them. Sadly, sixteen inches wasn’t enough longitudinal space to get an effective cross-flow SpinTech muffler.
We were warned this would be a rather loud, un-restrictive muffler design. Separate resonators would be a must and we would need an external cross-over pipe as well. This deviated quite a bit from our initial design and somewhat contradicted our original goals.
On the other hand Ron was very optimistic about the resulting system’s flow characteristics and said it would by far be the higher performing layout compared to a larger, quieter, boxier muffler that might not need resonators but would still be too short for cross-flow anyway.
Ron has spec’d plenty of angled mufflers in the past, ours just looks like two of them fused together at the spine. Ron’s angled single mufflers tended to wind up on air-cooled VW and Porsche applications with the odd double four inch oval LS V8 jobbie for good measure:
All of this would be more complex and expensive than our design brief called for. However, it was also much more performance-oriented. With SpinTech’s made-to-order everything, we could get a fully custom stainless X-pipe for no more than list price. This would help mitigate the difficulty of building a tricky conjoined mid-pipe.
In the end we went mad with the acquisition of parts. Including the initial cost of the oval elbows we spent some $1300 acquiring 304 stainless components from SpinTech, Vibrant, and Summit Racing.
We left no stone un-turned with all new stainless flanges, hardware, and exhaust hangers.
SpinTech sold us everything we used aside from v-band clamps from Summit and stainless bottle resonators from Vibrant Performance. SpinTech was great with the little things. For instance, their exhaust hanger kits come with OEM-grade rubber insulators and can be upgraded to stainless hardware at a reasonable price.
This meant we could buy parts, throw them all in a big pile at Tim’s shop, and be sure that there would be no hold-ups with fabrication.
So we did.
All the time spent measuring and communicating back and forth with Tim and Ron paid off when our parts fit together like an OEM product. The glorious mid-pipe stood out especially. We were really happy it ended up being a part of the build rather than the plain-jane pair of straight pipes our original design called for.
Everything was built around the muffler, which was even madder in steel than it was on paper. The four sets of spirals fall short on the six or eight there might be in a really quiet SpinTech muffler.
This made resonators a necessity. We were pleased with the inexpensive bottle units from Vibrant, but lamented slightly in our choice of the smaller 12 inch long resonators when it turned out the longer 18 inch version would have fit.
We’d have regretted the decision a lot more if the finished exhaust system hadn’t turned out to be plenty quiet enough for our liking anyway.
Our stack of exhaust components went together very nicely in the eyes of our fabricator. While looks are subjective, it’s a great sound that we ultimately most wanted out of this project. See what our finished custom cat-back exhaust system looked and sounded like next week on Project Hoondy!