350Z /Skyline 350GT owners... Grounding kits???

[Blue Meanie]

OK, over the ond here, there is a lot of talk, and thumbs up for 'grounding kits'. Now they seem to be popular on the 350Z's, and the offcuts, (G35, Skyline 350GT). Has anyone here used one, or heard of it? I'm not skeptical, so to speak, but it seems funny that a grounding kit could improve an engine. Why wouldn't it come that way from the factory???
http://www.g35parts.com/9083/osc/product_info.php?...

Oh, and has anyone tried the plenum spacers?? Good for 10whp+, apparently, and the owners verify it.
http://www.motordyneengineering.com/G35.htm

[martinmac]

Have a Spills grounding kit on the Zed and it does seem to smooth things out somewhat, as for other mods to gain power the ECU is a clever little thing and equals out the gains pretty quickly.