Armytrix never gave any guarantee, but a lot of people do not know that. they see posts from happy customers about the no CEL and they think thats a guarantee. when in fact it's not. it's not Armytrix's fault.
I'm unfamiliar with what happened with the other vendor, but they made an excellent point about the lack of a no CEL warranty. Armytrix will not replace the downpipe if you get a CEL.
It's all great if it works fine, but once it does not, you lose a lot of money on a very expensive catless...
in terms of power, you can go with any downpipe 4" or larger.
the 4.5" inch is the standard that every company uses, MAD and MST offer larger downpipes
the larger the mid section is, the deeper the downpipe tone. its not about adding power, but rather changing the sound.
They all need to neck down to fit the midpipe without modification, even the standard 4.5" downpipe.
in terms of performance, it wont make a difference on the stock turbo, but the sound is different than your standard downpipe. its got a deeper midrange tone.
Completely agree with you, get the best deal from a reputable place.
Here are a few things that can go wrong with a non-reputable downpipe or manufacturer
Stainless steel quality: 304 stainless steel. This happens way to often when customers have purchased products from less reputable brands...
Not familiar with them, but I recommend the MAD brand instead. it's very popular in the Supra and and BMW world, and comes with a lifetime warranty
they offer the standard 4.5" for $259 with free shipping
https://mad-us.com/mad-b58-downpipe-w-bracket-bmw-f-g-chassis-supra/
and the 5" fat boy...
I've been running my business for 11 years, and mistakes can happen; often, it's no fault of the vendor, especially when items are shipped directly from the manufacturer. In this case, your vendor acts as the middle man, forwarding messages and dealing with angry customers' wrath. ?
However...