Originally Posted by r1harper

well i have ran the RB S5 before and it was a very good engine..i had it worked by RB Mods and it was a beast afterwords as well and would go 9 min with a 086/long header. but i do think the P5 is stronger everywhere(in stock form)...and i have not driven back to back with the plus 4...all i can say is the plus 4 is smoother. I like the P5 alot though..and might like it even more in a week or so.....right Monty