600 hp LSx with 2.5" exhaust?

[streetk14]

Alright fellas, I have a little bit of a problem. I am going to need to modify my exhaust to fit the new Art Morrison frame I just put in. I'm not too happy about this since I was very happy with the way my exhaust fit, looked and sounded. FYI, the exhaust is Stainless Works 1 3/4" long tubes into a 2.5" X-pipe, Flowmaster Hushpower II's then full tailpipes over the rear axle. The entire system is stainless steel.

The motor is a Magnacharged LS1 based motor that put down 505 rwhp on the dyno. That's over 600 hp at the flywheel, and that was through a full length 2.5" exhaust system. Since I am going to need to change my exhaust at least a little bit, I was thinking about upgrading to a 3" system.

Do you guys think I will see a worthwhile power gain from the bigger exhaust? I would think the 2.5" system would be a bit of a restriction at 600 hp, but I don't have too much experience with supercharged or LSx series motors.

So this brings me to the next problem: a 3" rear-exit exhaust system will be VERY diffucult to pull off with my HTH truckarm rear suspension. The 2.5" system I have is a tight fit at a few points, so the 3" is probably not happening. So I am considering doing a side-exit exhaust system.

What are your thoughts on doing a 3" (or 2.5") side-exit exhaust system? I would have to eliminate the x-pipe and run without any kind of crossover. This system would be light-weight and easy to remove if needed, but I am worried about sound levels and resonance inside the car. I am also curious what it is going to do to the exhaust tone. I am also thinking about power/torque losses from getting rid of the x-pipe. I'm not sure if that would be anything to worry about, but I'm trying to figure out my best plan of action. Thanks,
Andy

BTW, Here is a shot of the way my exhaust was just before I took it apart to swap the subframe: