Impreza turbo 2000 make 300hp with cat in still?
 

my impreza turbo 2000 has a td05, newage wrx intercooler, yellow injectors, 2.5inch cat back, will it still reach 300hp with the cat still in, after a remap? or decat needed?

depends on what the TD05 is

16g

you will probably see your 300. but the td05 is a slow spooler in my opinion and the cat is just going to worsen things further. you could pick up a decat DP very cheap if you keep your eyes open.

I had a similar setup to that years ago on a 2000 classic with full decat. spooled around 3300rpm @1.4 bar but once going was a strong turbo but wasn't the best in 1st and 2nd,

depends what you want the car for I suppose.

aaron.

i may aswell decat it tbh, anything around the 300hp will be good enough for me

Fit a high flow sports cat if you're worried about MOT time.