I've been using smog doctor a few years now on various cars, both petrol and diesel. I have to commend them on their products. I use vb27,vb35 & vb45 all in conjunction. I've had problems before with injectors in a diesel. The car would chug if it was given any throttle due to very bad diesel blocking the injectors. This went on for a week until I threw in vb35 and within 5 minutes of driving, gone. Chugging completely gone. I've used the vb27 for NCT emissions. The NCT emissions compared to before i started using Smog Doctor and after are amazing. The emission levels are now below 1% of the threshold. I'm seriously not joking. Finally I use the vb45 on my Turbo diesel and my high mileage throttle bodied petrol. My turbo diesel, which has nearly 130k miles the turbo inlet fins look brand new by spraying this directly into the turbo as a 2nd person rev's to spool up the turbo. On the Petrol. the butterfly valve on the throttle body had a significant amount of carbon deposits and general dirt from seeing 230k miles. I sprayed the vb45 on and around the throttlebody intake and it almost imeadiately restored the brassy shiny of the valve, the vb45 is suppose to clean the intake plenum, intake valves and combustion chamber when used in this manner also but i havent taken apart the top half of the engine to inspect. So yes long winded review but i stand by all the Smog Doctor products for engine restoration without having to start taking things apart.