Trying to get some feedback on anyone's experience with dynoing the same car (with same mods) on the same Dyno but in vastly different weather conditions. Back in February, after installing plm headers and catless mid-pipes I dynod the car on a 55 degree day. It made great numbers at 458 rwhp. That was using std correction, sae was 443. While on the way home from the dyno my cel came on and a quick scan revealed typical "cat system efficiency below threshold" codes. That was a surprise because I was told the v7 turned off that cel. No problem though, Jerry got it straightened out and I reinstalled the tune. At the same time I replaced the injectors when that good deal was going on. As documented in my injector thread, several of them were pretty carbed up. So I figured with a new tune file installed and new injectors I'd go back to the dyno and see if the previous numbers had been improved upon. To my surprise, the car only put down 443 rwhp (431 sae). Obviously I wasn't thrilled but wrote it off to the temp being 85 this time. However, I had also changed two other variables by installing a different tune file and changing the injectors. So that got me to thinking...was the tune any different (I was assured it wasn't) or were the new injectors not up to task (probably not the case) or could weather make that big of an impact on the numbers? I was surprised that even on a very warm day, the software still corrected the numbers down, not up, using a cf of .98. So what I'm wondering is could 30 degree warmer weather cause a 15 hp loss even with correction? And why would it still correct down at 85 degrees? I know humidity and pressure factor in but that was surprising. Just wondering if anyone has experienced anything similar? I've probably made about a hundred pulls over the last 30 years, but have never had the opportunity or need to dyno the same car, same mods, same machine, but much different weather.