i spent many hours going through all the bolt on turbos ( kinugawa, kando, arashi, mamba, forced performance, blouch etc ) and mamba makes some nice twin scroll bolt on gtx turbos. take a look at this, might do the trick. could have tdo5/6 twin scroll too not sure
https://shop.mambatek.com/product.sc?productId=546&categoryId=13
or a 3 inch inlet version
https://shop.mambatek.com/product.sc?productId=3031&categoryId=13
can be pretty confusing looking through the turbos on that site and all the different versions but the twin scroll ones say they are spec c
would be good if forced performance made twin scroll but they seem to have crazy good spool on single scroll and journal bearing they feel they dont need to i gather. forced performance was my first choice before i decided to go twisted efr.
mamba turbos is by the founder of kinugawa turbos before something went down and he left and started again
edit: whoops those ones have the middle scroll removed (says high flow) to make more peak hp but theres others that dont i think.