Originally Posted by MD SRT6
OK alot of you will dismiss this as crazy, but my theory on the pulleys is 178mm is perfect. Any larger and you start to reduce power. There have been some company's promoting the other sizes and showed some higher boost levels, But no one including myself to date anyway has benefitted on the track from them. I believe the trade off between the extra heat etc.. reduces power. Renntech and evosport etc whom are large companies with big budgets have studied this, what is safe and produces peak power. I ran 12.08 on the 178mm pulley and have not done any better with the 181mm with all the same parameters. In fact I've been slower and yes I have adjusted tune for it. That is why I started the 178/181/185 thread. Anyone who has run faster than a car with a 178mm pulley on a 1/4 mile track with a 181 or 185 please chime in!
I had noticed the same thing when reading threads on people running the different pulleys. Unless you have the extra cooling then you will not be making any more power/possibly less with the extra boost. If you would add headers and maybe some exhaust cutouts you may see the power come back.