HELP please. Do these work any1 used before?

[nuki]

This sounds just the thing i need. My car reads KPM and is still restricted to jap spec 112mph or whatever it is. Has anybody had any dealings with these? or does it create problems with the ecu etc? thank you.
 
http://cgi.ebay.co.uk/MAZDA-BONGO-RX7-SPEEDO-DELIMITER-CHIP_W0QQitemZ180344216300QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item180344216300&_trksid=p3286.c0.m14&_trkparms=66%3A4%7C65%3A7%7C39%3A1%7C240%3A1318

[RobMatthews]

yes thats the sorta thing you want you want they do not interfere with the ecu or anything else,fit behind the speedo clocks you do have to snip a wire though. not used that seller befor but i got mine from ebay.

[AshRX]

cheap way of doing it dude and sometimes they can play up. Best bet would be to get a PFC

[philiwily]

Thats what you want, think i would try find someone with a better feedback score though. If you do a search on here you will find out how its done.
Phil