By alley - Jul 12, 2014, 12:11 PM ET

IMSA: Extreme Speed shows extreme speed in Mosport final practice

Yesterday we showed you an

onboard lap of Canadian Tire Motorsports Park

with Ryan Dalziel, and today his Extreme Speed Motorsports HPD was the place to be if you wanted to be fastest in final practice for the Mobil 1 SportsCar Grand Prix presented by Hawk Performance. The Scot lapped the 2.459-mile course in just 1min09.996sec during final practice to edge Richard Westbrook's Spirit of Daytona Corvette DP by a little under quarter of a second.

Joao Barbosa was a further six-tenths of a second adrift in the Action Express Racing No. 5 Corvette DP, while Gustavo Yacaman's OAK Racing Morgan-Nissan was almost 1.7sec off the ultimate pace. However, we suspect this apparent languidness from yesterday's pacesetter was because the team knows it has the one-lap speed necessary to contend for pole and had turned its attention to race setups.

In GTLM, Dirk Muller put the No. 56 BMW Z4 GTE (BELOW) back on top by just 0.038sec ahead of Antonio Garcia's Corvette C7.R, but 0.2sec ahead of the No. 91 Dodge SRT Viper GTS-R, driven by Marc Goossens. Again, the Falken Tire Porsche of Wolf Henzler was the fastest of the 911s, fifth in class and around half a second off the lead BMW.

However, Porsches led the GTD class, with Horton Autosport's Kevin Estre remaining top of the charts, albeit with less than one-tenth of a second in hand over Leh Keen's Alex Job Racing entry. Third fastest was James Davison in the TRG-AMR Aston Martin Vantage.

Qualifying for the Mobil 1 SportsCar Grand Prix starts at 5.20 p.m. ET.

• To find out what GTD-class team principals think of the TUDOR United SportsCar Championship, read Marshall Pruett's story here.