Stock exhaust with a dump pipe will flow 380kw but its getting to its limit but it won't attract attention. Muffler delete could of also been done as well.
Power seems about right for a 3582 on pump fuel (98)
Gearbox will be fine at that power as long as it hasnt been belted everyday. You will know when you drive it whats that's like. Check for whinning, and how it shifts to start with, then randoms etc coming from the driveline
Overall car will be fine, power is decent and wont need to do anything except enjoy it. Perfectly safe at that power.