I've done a lot of research on pipes to decifer which does what.Thus,
FMF Gnarly, part no 020055, is a good performer for low end through midrange pipe, but signs off early.ran an 88-04 pipe of this type on my 86 B2.
FMF Gnarly, (desert) part no 020038, is the mid top pipe of this brand, never ran one but many members have.
Pro Circuit Works/Platinum, (part nos change on PC pipes to show year so an 86 plat pipe is pk86500p.87 would be pk87500p, etc etc.)These pipes share the same cone shape, the Works being unplated, the Platinum is plated.These are pro Circuits mid through top end pipes.
Pro Circuit Platinum 2, part no pk86500p2, or pk87500p2 etc etc, is Pro Circuits low to mid pipe.
Hope this clears up which pipe does what, so now all you need to decide is how many rpm's you want to be pulling when you smoke them diesels.........K.