I run the Holley Street Dominator with a Holley 850 DP on my 440 that makes about 500 flywheel HP. I have a 1" spacer on it and it fits under my flat hood with no problems. I like the Performer RPM and the Holley Street Dominator alot for mild street/strip bigblocks. But the RPM is higher and wont clear some flat hoods so I went with the Holley SD and the 850 DP and I love it as they work great for me. Ron