Subaru 2.5 fully forged rebuild MD321v turbo, rcm headers and uprated injectors. Wanted to know do I need a high rated up pipe? Thanks

 

If you already have an sti up pipe it won't cause a restriction but fitting a trick up pipe will improve spool by 2-500 rpm dependant on your set up.
Harvey smith/a s performance and the rcm up pipes will do that job nicely.
Hth

Siv

 

Get an AS performance Harvey up pipe. Great bit of kit