normally aspirated engine performance comes at a cost, an exhaust by pass valve will not produce any gains apart from noise, might be good for street cred but on a track day they have noise limits and that will get thrown out.
if serious about track days you would be better remembering the golden rule. BHP per Ton
remove all the seats, carpets, and any extra weight and that will make more difference than any exhaust by pass valve.
if not the list starts to get expensive
big valve gas flowed head.
forged crank
H rods
light weight fly wheel with competition clutch
light weight HC pistons
High lift cam
full flow ex manifold and exhaust system
re worked inlet manifold
high flow injectors and fuel pump, with swirl tank to stop fuel starvation
and then a remap to get the best out of the 5k you just spent.
you might see 30+ bhp extra a lot to spend for 30bhp
and then of course you have to be able to stop the thing.
AP 6 pot callipers and rotors, braided brake lines.
handling, some coil overs required, Olin's being tops but at 5 to 6K a set OTT even so something half decent will be 1k min.
much cheaper to buy a golf Mk4 gti. remap it with the K03s turbo for 200BHP the 20v engine is solid, AGU being the strongest of all in the early MK4 golfs 19mm wrist pins engine code AGU unlike later ones with 17mm wrist pins.
there you have the basis of a track day car. a Jazz just isn't track day material with out spending a fortune on it.
an exhaust by pass valve might have a fun side on street cred look fast cars for noise only effect, but that's about all.
the best performance gain is ditch the weight! simple's