Rough on the engine?

I have a 2000 SL1 with 25,000 miles on it. I was just wondering, is it bad to be rough with this engine (1.9L SOHC (STOCK) obviously) alot?

I have an automatic.

I mean I dont have the resources to replace the stock internals but I have thought about a head swap with the DOHC head.

only 25k? sure! not a problem, but be careful w/the tranny