Would have to echo the owners here that touted the attributes of the Corsa. The R & D is superb and they sound killer under power and idle , but just do not have the annoying drone of the Borla. For a catback, I think they are the absolutely best, but then we have gotten such fabulous customer service from them over the years, and that has enhanced the product.
Kinda nice to get a product built in the US ( Ohio ) by hand, knowing the unit was dyno'd and built to produce the most power with the best sound , sans an annoying drone. This system is literally tuned to each make of car/truck they build their units for and with no internal packing , they last forever.