On Mark's 1600 I recently made a new exhaust system for him... we dynoed the before and after and there was an almost 3kw increase at the wheels, though the first day (on a tuesday) with the middle muffler it was 33 degrees and the second day on the friday it was 42 degrees... thats degrees Celcius BTW, so about 110 on the F scale...and the dyno we used didn't have any sort of temperature correction, just raw figures.
up top is the standard ansa type muffler the engine was originally dynoed with in 2018 and made 109 rear wheel hp, in the middle is a stainless system Mark had made by a local (in sydney) expert but Mark said it felt like it dropped power (which was fitted on the tueday in december dyno run), and bottom is the 2 1/4 inch mandrel bend, 2 1/4 internal tube "triple flow" muffler and 2 1/4 tailpipe exhaust system I welded together for him and was fitted for the Friday dyno run.
View attachment 81652
all three systems fit onto the same ansa copy 4/2 extractors, all exit in the same place in the bodywork, all mount to the same standard factory exhaust mounts.
The car is noticeably faster with the new exhaust system, and late next week we are going back to the original dyno we used back in 2018 to get some comparative figures... the same basic engine combo, just now with a better muffler, 36mm chokes up from 34mm chokes in the 40mm DCNF's and different (short) auxiliary venturis and slightly larger main jets, we want to see if it's topped 109wheel hp / 120 lb/ft torque from these couple of changes.
SteveC