if you have money to spend like that... i would've went with a all N/A setup... which idk if you prefer it .. but get some really good internals.... spend couple of grand on the internals... starting with the crank ( balanced and knifed ) with new pistons, rods, cams, lifts, retainers, ) from what i heard on a diff forum from BIGV that with the nismo crank pistons and rods the ka can actually achieve 10k rpm with no load ( now idk if a sr can do that

)
and rev higher than a sr with load
and as soon your bullet proofed the engine... do the exhaust and the intakes... get a new head or get it machined.. then just get a good ecu tune...
if you have money to spare you can prolly make a good 300hp to the crank even more (of course not with just what i listed, prolly more to it... im still studying )
and the GREAT part about it is that it will last WAYYYYYYYY longer than a turbo...( not much rebuilding of the block and turbo itself )
and also solves your problem.... from cops it will just look like a reg ka24... but they don't know the rest that's been tuned and transformed... and you don't need boost gauges for this... so it saves you all the headaches while giving your more of a torque curve than an sr...
and you will have the nice power band also of a N/A~ ( no boost lag ) hehe...
just my .o2