have had dual nozzles in my aluminum front mount ic pipes for years (since 2003) no signs of any issue
even used an aluminum coolant reservoir for alky (always 100% methanol)
find something else to be neurotic about
i will say alky is very bad for rear tire life and driveline parts may break sooner
I've had a double nozzle shooting into an aluminum up pipe for over 20 years. No issues here.
It's also shooting into an aluminum dog house and intake manifold.