Yes, all JZ engines have small exhaust ports and restrictive manifolds. The purpose of this is to keep exhaust gas velocity high, thus encouraging quick spool-up. That's the reason a 1JZ is amazingly torquey for a 2.5 litre engine.
And yes, there are plenty of gains to be had by opening up those ports and replacing the stock manifolding with something a bit bigger.
Mon, 29 March 2004 23:16
