You can tune a car for higher load in the lower range, both ecu and tcm. Mainly tcm and convertor slip, second gear start, use the torque model to cover torque load and delivery.
Bolt-ons are typically chosen for high rpm peak, for example typical OTR is not ideal for low rpm delivery.
Sure Di Filipo headers as suggested have a torque ring / accelerator in the collector to overcome the typical problem of high load at low rpm, but is not the same as low rpm tuned length scavaging.
Other header designs are specifically made to deliver torque earlier but they will not sound like 4-1 with the kiss that I gather you are looking for.
Here is an engine tuned for high load off idle, plenty of stock convertor slip and second gear take-off.
Deep sound but from 4-2-1 and x-pipe at tuned location for low rpm scavenging:
Result is more old school hydralastic 20 Kph to 100+ without much steam or scream:
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