Both engines are very easy to tune and they both perform very well. The Vspec has more low end initial punch where as the P5 comes in a little smoother but still has plenty of punch. The P5 will last alot longer than the vspec if treated properly. I can't say much about the B5 or Alpha line as I have not run them but so far guys are liking them alot but when it comes to track reputation over the years, the P5 has more than all 3 of them combined. The B5 and Alpha line does look good from a stand point but ask around in 6 months or so and see if guys are still raving about them. They might and they might not. Time will tell but one thing is for sure, the P5 will still be there and still running with and outlasting most. If you want a P5, i have them in stock and can hook you up with a great deal.