is there away into ecu to change ign timing?

[zen]

is there away to get at ignition timing on 95 (gen 2 )ls400 ecu and engine?

or will i be needing aftermarket standalone/piggyback ecu?..if so which one does you reccomend?

reason for asking....supercharger setup now ready to install(m112..6psi as skinny rods)..AND running lpg (propane)..(need to advance timing lots for lpg)

please cash is limited at present (as just installed £1200 of lsd's ,both front and rear)..so if there is a back door way in to ecu it would be nice (untill funds restore themselves..)

thanks