It does improve throttle response , but the main benefit is when the boost is increased there is no expansion which means no lost boost pressure.
They look cool , but not being a fan of polished things I am having mine anodized , havn't decided the colour yet , but it won't b red or blue !
Bit of an exageration there m8 , flexibles won't expand 2 x2 , but they do expand both radially and longitudinally , doesn't take much of that 2 loose pressure , and if energy is absorbed there it ain't going in2 the engine. Flexibles also deteriorate as they age.
Most serious comp turbo comp cars have totally hard pipe with special joints 2 absorb heat expansion and vibration , 2 expensive 4 production line road cars.
Depends wot stage u want 2 go 2 , 4 stock boost or close 2 it , the hard pipe kit is not cost effective , but from 1.4'ish bar up it's a good idea.