Is it safe to run the following mods on an MY03 WRX for a short time without a remap?

STi Decat up-pipe
Prodrive Sports cat downpipe
STi Decat centre pipe
Deresonated centre section
TSL Panel filter

Also is it worth upgrading the fuel pump for these mods or not?

 

It has been stated by some that these mods can be driven without a remap, but you wont get the benefit of an optimized output. To tell you the truth, I am midway into doing the same(except for an H and S decat downpipe) with my MY02 WRX.

 

I have identical mods on my MY05 WRX. I was advised that an uprated fuel pump was advisable, but not absolutely necessary. (So I did). The std pump is ok up to around 300bhp, these mods will give you 280-290 after a remap.

I had mine mapped same day as parts were fitted so don't know how safe it is, but I gather that if you drive gently, you should be ok.

 

IMHO if the car runs o.k. and doesn't suffer from boost spikes then it will be o.k.
Common sense says that you should avoid lots of revs and boost, but some of us end up travelling miles to a mapper.
HTH
DunxC