Would it be worth upgrading the fuel pump in my sti 4? It is standard apart from a blitz cat back system and K&N Filter.
I get an amber light every now and then on the knock link. Just wondered if upgrading the pump would?? (Engine done 69500, mobil 1 15w50 every 3k, run exclusivly on optimax )

 

if you are not planning on any more upgrades then an uprated pump would be a waste of money.

you would be better off spending on a few bottles of NF to keep the det at bay.

if you are planning more mods then a walbro 255l pump and an SX reg would be a good idea.

 

What if the the cat pipe (between DP and Blitz) would be exchanged for a Scoobyworld de-cat "cat" pipe? Would a Walbro be needed then?

 

No one knows? My car is a STi MY04.

 

there is a chance your pump is running a bit lean, they are known for dropping off as the miles increase, i know mine was

the fueling was always a touch to lean

might be worth thinking about
i replaced mine with a sti8 unit with only 250 miles on it from ebay £20 deliverd