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I wasn't able to find a definitive answer to this question searching through other threads, but essentially I want to know exactly what size OD tubing to order for the bypass mod on my stock Ti exhaust. I've seen people use 1.25", 1.5", 1.625", 1.67", 1.75", etc. Some say certain sizes are louder and certain sizes produce more raspiness and worsen the tone. I've grown very tired of my B&B Bullets after installing LT's and no cats, especially since I started using my Z as a daily, and I'm still on my stock cam. I can only imagine it would be even worse once I get around to doing the BTR Stage 2.
Basically, the larger the diameter, the louder and potentially raspier it gets. There is no "correct" answer to your question as it all depends on personal preference. Virtually any diameter will be quieter than your B&Bs. It's really hard to answer, because I don't know exactly what you're going for.
Last edited by MWWarlord; Feb 24, 2021 at 02:16 PM.
Reason: Spelling
You might PM forum member KITT, if he doesn't see and respond to this thread. I believe I remember correctly that he has personally done the Ti bypass mod before and may be able to provide you with specific info.
I think I went with 1.75" when I did the bypass mod on my Magnaflows. Can't remember exactly but looks like it was 1.75" or so. I have basically zero drone (super minimal), I couldn't be happier with the volume. Here's my original post of my experience. https://www.corvetteforum.com/forums...aflow-xls.html
Last edited by turabo87; Feb 24, 2021 at 03:41 PM.
So what would be the largest size possible to run? I'd assume it would be the same diameter as the outlet tubes that lead to the tips, of which size I don't know and am currently not in the same area as the exhaust to measure.
St. Jude Donor '14-'15-'16-'17-'18-'19-'20-'21-'22-'23
Originally Posted by turabo87
I think I went with 1.75" when I did the bypass mod on my Magnaflows. Can't remember exactly but looks like it was 1.75" or so. I have basically zero drone (super minimal), I couldn't be happier with the volume. Here's my original post of my experience. https://www.corvetteforum.com/forums...aflow-xls.html
My opinion is that the diameter selection is basically a range of tradeoff between how much gas is being bypassed during WOT vs muffling sound during cruise and idle. So yes, the larger diameters will bypass way more on WOT and also still bypass some on cruise and idle, and the bias between the two will be larger in proportion to how large the diameter is. All common sense. I think if you go TOO BIG (such as the same diameter of the muffler tube which is about 2-2.5"), you will lose almost all the bypass/ dual mode nature of the bypass mod, and your mufflers will do less of a muffling job even on cruise and idle, making it almost a straight pipe exhaust. The BIG difference between the bypass mod and a straight pipe exhaust is that the mufflers help create a sort of Helmholtz chamber that help take the drone out of the exhaust. That's why you hear almost no complain of drone with bypass mod folks. Case in point, my car believe it or not, has near zero drone and the stock Magnaflows drone more than with the bypass mod.
Not sure if this is relevant, because I don't have Ti exhaust. But i had the bypass mod done just before putting the car away for the winter. So I actually have only driven it home from the exhaust shop. Anyway, one of my replies on the attached thread has sound recording of before and after. I used 1.5" bypass tube.
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Slideshow: A Jaguar designer's personal project imagines what a modern front-engined Corvette might look like if Chevrolet revisited the golden age of the Stingray.
Best diameter for Ti bypass mod?
