Currently I have a Catted BBK H and A/T cat-back on my 97 Cobra.
I'm looking to change that to BBK long-tube headers, BBK O/R H, and Magnapack cat-back.
Am I going to benefit from this... enough to make the money worth it?
I had 3 chamber flowmaster catback and a Bassani X pipe. I decided to ditch the flowmaster catback for the magnaflow catback. When I did the switch I noticed the car had some more top end (above 4k) pull- but felt alittle weaker under 3k rpms. The total money I laid out for the switch was the $315 for the flowmasters and $260 for the magnaflows. I was able to sell the flows later for $150. I think the quality and sound of the Magnaflows was worth the money.
As someone who has made the cat back swap your thinking of and laid out the $$$ I'm really not convinced that the price of the exhaust swap is worth it, but if you have money to spare then I'd do it since the Magnaflow quality is better and its stainless. If money is more of an issue then instead of ditching the flows why not buy pullies for the car?
As far as your H pipe and the long tubes. You could just get rid of the cats on the BBK yourself for free, so thats good but with the long tubes installed you will have to butcher it. That means most likely your gonna be buying a shorty pipe to work with the long tubes or spending about the same amount of money to modify your H pipe. However, I would still definately do the headers on the car.
In short- Keep the Flowmaster catback and spend the money on another mod. Do what you have to to your BBK H to make it work or buy a new shorty pipe and Definately do the headers.
If you do the headers yourself DO NOT use the supplied gaskets, they will blow out. Also remember you may have clearance issues becasue the headers hang down low and you will not be able to rip the trans out of the car quite so easily since the headers will be in the way.