Finally got a day with around around the same correction factor as the last time I dynod my car with the macs/orp to compare with the new (used) grotts. Nothing has been changed on this car except the headers, y-pipe and cat back, about 200 miles between dynos.. the first was the best out of 4 pulls with the car using MACs, catted mac Y with the cats gutted and a flowmaster collector through a magnaflow catback. 2nd is the best of 4 pulls from today with grotts, futral 3" y-pipe and flowmaster collector through a hooker catback. The a/f was a little richer today then it has been for the last 20 pulls or so but I just changed the filter in the wideband pump so that may have thrown it off a bit.

Anyhow, peak numbers didnt change that much but 10-13 rwhp under the curve looks pretty nice. Also, at the same track (london, KY) the car went from a best of 12.07 @ 115.2 (1.715 60') (Z06 clutch was on its way out though, had a hard time getting the car in 3rd) at 1500' DA to an easy 11.86 @ 116.6 (1.727 60') at 2853' DA through the exhaust after the grotts.

I still like MACS but I a pretty happy to gain the power under the curve for free (I sold my macs/y-pipes and magnaflow for the same I paid for this whole setup from jason 99TA - thanks man ) If I would have had my LS1edit cable with me today I could have leaned it out a bit and maybe made 410rwhp through the muffer with a 216/220 Comp Cam and a 12 bolt, not bad BTW, peak numbers were 403rwhp/390tq and 399/381 with the MACS - too lazy to make another pic.. The car has dynod higher peak HP with the macs on cooler days but the curve hasnt changed, looks way better with the Grotts.

 

That make me happier to have got those Grotts 3 years ago

 

Nice numbers Kevin! I'm glad my old exhaust setup found a good home.

Jason

 

BTW, I did this same swap awhile back (MACs --> Grots). I'll post the dyno graph in a few days.