Exhaust - is bigger better?

Question for the masses....for a car that's gonna be running close to or just over 500hp (N2O or blower + some other goodies in near-distant future ) - would you recommend short tube or long tube headers? 1 1/5" or 1 3/4"? 2 1/2" of 3" exhaust? Is it true that longtubes will take away some low end torque? Should I stick w/ my BBK 1 5/8" equal lengths shorties and just work back? Sorry for all the ?'s

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'90 LX 5.0;12K original miles (no sh*&);3.55 gears; March pulleys;Edelbrock Performer Heads;BBK 1 5/8" equal length shorties;MSD 6AL ignition w/ blaster 2 coil;FMS E303 cam;Pro-M 75mm MAF;BBK 70mm TB; Eibach drag-launch spring kit;Southside welded subs;9" K&N cone filter charger;Hurst shifter;Cervini's 3" turbo hood;A/C delete; gutted cats;2 chamber Flomasters;Corbeau racing seats;FMS 30# injectors;JMS chip; Holley 190lb fp;TFS track heat Intake (12.299 @ 113 - 1.78 60')