Cobras? Are they really that bad?

[Jgas]

Ok. I admit it. I just love the look and sound of dual cobras! Each side i mean. I have learned here that cobras aren't good overall performers. So..
Why don't they work? Not enough backpressure? Too much? Can i make them work better? What performance will i lose?? If y'all say no go I'll stick with drilled stock or something else. But i will be eaten alive with the "why not" monster! I found posts here regarding scavenging which i kinda understand from offroad racing. But 8 to 10 h.p. loss is a bunch! Not doubting your testing. Just really love looks and sound of the darn cobras! While I am asking dumb questions... are there any other twin slash cut 2 into 4s that work better? I can fab and weld a bit. Anyone made 4 voodoo mufflers work? I find them on parts sites really cheap. And that likely explains itself! Thanks again.

 

[Fire-medic]

The USA 4-outlet exhaust that works to produce power and NOISE is Jon Cornell's UFO Quadzillas. It's a complete system, NOT a slip-on.

I believe Mike Lee of Star Rider Performance is who assumed the UFO assets
StreetPro 4-2-4 Exhaust w/ Polished Quadzilla Mufflers - Ceramic Coated (85-07 All) - Star Rider Performance

He continues to support the Gen 1 VMax community with quality parts. Not cheap.

Cobra slip-ons are pretty, but they cost you power over an OEM exhaust. Because of that, I'm personally not-interested, however, if someone loves polishing his 4-into-4's and he loves the look, 'good on-ya.'

Cobras offer no scavenging.

Something many do-not know, the federal government got-after Yamaha because the 1985 VMax exhaust system did not-pass the federal standards in-place at its release. Yamaha implemented intake and exhaust changes for the 1986 model year. Their exhaust system became compliant, but it cost HP. To overcome the loss, the VBoost grew its I.D. by two millimeters.

You can ask Sean Morley about it, if you don't believe it here.

 

[Jgas]

Oh yes. I believe any and cases of big brother getting in the way! So this begs the question... the 85 and later looks the same externally. How do i make it the same internally as the 85? Larger header i reckon?

 

[Fire-medic]

I have an '85 megaphone sitting in storage but I don't know internal baffling differences, which is where I suspect the DOT problem was.

My advice is, ignore the difference, enjoy the ride. I suspect the 1985 and the 1986 front headers are the same but I don't know that for sure.

 

[Vinmax]

If the only thing changed was the exhaust canisters, then that would imply a simple slip-on would get back any actual loss of HP. And most tests comfirm that there is little to no difference in HP with a slip-on.
Maybe the most difference would be to optimize jetting. In that case, then you can pick up a couple HP's through optimized jetting and get a bit more noise and less weight if you go to a slip-on.

Vinnie