I have two, top of line, piggyback tuning chip systems for sale for Gen II VT 1.6l's. Initially I was going to do a comparison, but decided to do an actual ECU tune from QwikTyme instead. PayPal or money order.

1. RaceChip Top of Line GTS Black model is like new, on car less than 1200 miles & then infrequently used. German engineering is bluetooth enabled for smartphone control/ "tune" setting with RaceChip App. List new $528. Asking $325, shipped, in original box & with instruction manual. Reasonable offers considered.

2. TDI Tuning Chip system - a British system that is similar to the above & also bluetooth enabled for smartphone control through their app. This system was never installed, is New-in-Box. It lists for ca. $475; asking $325, shipped with full documentation. Reasonable offers considered.

Both are from reputable firms, with TDI apparently better known for Jags & other Brit brands, whereas RaceChip is seemingly more known worldwide. They are both essentially boost controllers, but TDI implies their algorithms do more than solely that. I never ran datalogs on the RaceChip, but butt dyno seemingly "reported" more boost. ;)