Best way to fix Boost Spike when fitting 4" Dump pipes to Fg Turbo / Territory Turbo

[TTR]

Can boost be limited with retune when a 4" dump has been fitted, or do the waste gates need to be ported / or even a external wastegate fitted?

2011 XR6T Manual. After fitting 4" dump pipe its loses boost when changing 2-3rd gear under hard acceleration, and then wont boost again until its been turned off for awhile. Only other mod is sports exhaust, 50% atmo blow off valve, and slightly bigger intercooler

2007 Territory Turbo. Only mods are a 4" Dump and sports exhaust and seems to now be boosting/spiking to 15psi and hitting some type of boost cut, but once it drops down starts boosting again.

Thanks

[45T-XR]

Yes, tune will fix it, or put the stock Cat back in.