Welcome. Maybe you could buy a period.
If you do a search on IMS you'll find a month's worth of reading on the topic. It has been beaten to a pulp. You can make your own judgements after reading up on it.
If you don't want to take the time to read about it, I'll give you a two sentence summary: Look for a Boxster that has had the IMS upgraded. If your dream car does not have the IMS upgraded, buy it at a reduced price and plan to spend $2K on a clutch & IMS upgrade.
Also, Porsche are not small block Chevys. You don't throw a few mods on them and open up another 50-100 hp. You can spend $5K on headers, cat deletes, high flow exhausts, and intake plenums and gain a collective total of 20 hp. If the Box does not provide the kick in the pants you're looking for, don't buy it because you'll never get the satisfaction you're looking for at a reasonable price. Boxsters were not meant to be drag racers. They are designed for handling / cornering. The only way you'll get substantial hp gains is by spending cubic dollars - as in $15-20K for an engine upgrade.
Many have gone down the road you're looking to traverse. I'm just telling you how that road ends before you go down it.
Good luck with your search.