The late turbos like on the 92 (I have a 90 turbo on my car, which is the same) you drove have almost no lag. There is most likely a different problem responsible for the lag. The T3 Garretts have lag, we also have one of those. You should be aware that there are more differences than just the compression in the Volvo turbo engines. The turbo heads have sodium cooled exhaust valves. The turbo blocks have oil supply and oil drain ports for the turbos. The turbo cam is different. The ignition control module and the fuel injection ECU are differnet on the turbo cars. The turbo fuel injectors are rated for higher fuel flows and must be powered through a resisistor ballast pack. The turbo cars use a stronger clutch on manual tranny cars, and the automatic cars use a slightly different transmission. The turbo cars also use different ratio differentials, and all the turbo differentials are the heavy duty model.