you can do both of these, but it’s highly recommended not to.
for the intercooler, technically you can just make a pipe to go from the turbo to throttle body, but why bother spending money to make this when a stock sidemount setup with piping is only $100? also the intercooler is very good to have in the event that you blow a turbo, it will stop bits of turbo from going into the engine which will almost always ruin it. if you just put a pipe from the turbo to the throttle body without a blow off valve it’s VERY bad for the turbo.
a stock (of aftermarket) KA exhaust can be modified to fit an SR, but it’s very restrictive and will really hold back the potential of an SR, and when you factor in spending $60-100 to have the exhaust modified to fit, you might as well have just put that money towards a proper 3" exhaust which can be had for $300 or less.
good luck.