I give a huge vote to Larini. I installed it myself, (98 Diablo) and the difference is day and night. I thought I heard the car say "thank you I can breath now"!

The sound is also perfect for the car, a snarling mean sound. I can definitely feel a difference in power, but can't say how much at least 22 HP though. (rear cats removed).

I also chose Larini because I got sick of everybody touting Tubi. It's too expensive and they are getting a premium because of the "heard" mentality.

Lastly, whatever you decide anything is better than stock!