I love the sound of the exhaust. It's perfect; very quiet under part or constant throttle but very sporty when accelerating. Absolutely NO drone whatsoever. It's loud enough to say "sports car" but not so loud as to be obnoxious. Not any louder than the stock exhaust at cruise. I probably will not roll my windows up till next June, it just sounds that good.
My recommendations for installation:
- Use a high temp RTV designed for exhaust systems when assembling
- Torque bolts to 25 ft lbs and check for leaks with the car still on the lift/stands
- Start install at the cats, then secure and fully tighten the crossover connection before moving to the rear.
- Jack stands work great for supporting the pipes when assembling
- Be sure to remove the hanger extension near the differential and add a spacer when reinstalling the bolt.
- Don't bother trying to wrestle the rubber hangers off the stock components. Just unbolt the brackets and remove the rubber when the pieces are on the ground and accessible. Use a silicone lubricant on the rubber to aid removal.
- Have two box end wrenches for the crossover bolts, preferably offset box end wrenches to avoid rounding the bolt heads and busting your knuckles
Using the silicone will require a 24 hour wait before returning the vehicle to service but I'm not sure if the connections will be tight enough to seal at the recommended torque value for the bolts provided without the sealant. Perhaps the next person to install an HKS can chime in. I'm certain you don't want to break the bolts on the cats by over torquing because they are tack welded to the flange and that would be a major pain to drill out and grind the flange flat for another bolt, so tread lightly. Mine did not at 45 ft lbs but I don't know how the constant stress from heating and cooling will affect them over time. On a positive note if they do break I guess it'll be a good excuse to replace the cats with HFCs.