Had the prototype set for almost 3yrs/~40k now, only have minor complaints. Performance-wise: they're great, can't ask for anything more than what I saw for dyno testing (
24.7whp gain back when I only had just under 260whp with mani's & Gen3/3.3"/XP
Issues that can be taken care of before install... add a $40 ZZP 3" flex, and get them ceramic coated beforehand, if available. Otherwise you need to keep up on engine bay detailing with a stainless cleaner, or that sexy gold gets hidden by some crud over time, and takes alot of work to clean off. (don't know why they say 1-3/4" primary and mild steel... these are identical dimensions to SLP's and made of
321 stainless, a version of 304... Zoomer & I both confirmed this with magnet testing)
I, personally, had no issues with welds, but others have. As with any header, check them over before install to make sure they're ready to go. Buy the good Torca AccuSeal clamps, and use copper RTV in the slip-joints if you're worried about leaking there. The same care & attention to detail needs to be taken with all header installs, in various ways.
I give them 3.5 out of 5 torque-stars, especially with the new v-band downpipe split, making install much easier than the old versions & SLP's. Lack of coating, clamps, and 10-15k mile flex are the reasons for this grade. Silver Ceramic TOG's are probably 4-4.5 in my book, with original coated SLP's and regular coated TOG's at ~4. Pacesetters and S&S's are down in the SSAC territory, due to various drawbacks they each have as well, including mild steel construction, with coated versions around 3.5-4.
My opinion based on many installs and witnessing of performance numbers afterwards. All headers will give a similar performance gain, so it's the other aspects that' you're choosing between, including price obviously.
- Dave