I still recommend it, best cai out on the market.
Next to TPR, anyway.
TPR = 0 CELs, 0 bogging.
Hand made? How would a slight bend in the pipe, or perhaps an improper weld trigger a CEL?
The MAFS mounts were 100% hand welded, and more often than not, they weren't welded at a perfectly parallel angle to the piping. This caused the MAFS to be at the wrong angle, , making air bypass it instead of flowing up through it. This caused CELs a lot more than they would've occurred with a machine aligning the mount.
Does the cel effect the car's performance in any way?
Yes. The car goes into safe mode, and sets the AF ratios to rich, since the CEL is caused by the engine running lean. It's a safety measure so the engine's internals don't overheat (lean = hot, rich = cool), and it results in reduced power output.